Replace name attribute with setters and getters in the C API of mjSpec.

PiperOrigin-RevId: 778816015
Change-Id: Ieffb7a5bce37e887ff009f9a02d2434435e79ca1

doc/APIreference/functions.rst

@@ -4228,6 +4228,15 @@ Return spec's next element; return NULL if element is last.
 
 Attribute setters
 ^^^^^^^^^^^^^^^^^
+.. _mjs_setName:
+
+`mjs_setName <#mjs_setName>`__
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. mujoco-include:: mjs_setName
+
+Set element's name.
+
 .. _mjs_setBuffer:
 
 `mjs_setBuffer <#mjs_setBuffer>`__
@@ -4331,6 +4340,15 @@ Set plugin attributes.
 
 Attribute getters
 ^^^^^^^^^^^^^^^^^
+.. _mjs_getName:
+
+`mjs_getName <#mjs_getName>`__
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. mujoco-include:: mjs_getName
+
+Get element's name.
+
 .. _mjs_getString:
 
 `mjs_getString <#mjs_getString>`__

doc/includes/references.h

@@ -1875,7 +1875,6 @@ typedef struct mjsPlugin_ {        // plugin specification
 } mjsPlugin;
 typedef struct mjsBody_ {          // body specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjString* childclass;            // childclass name
 
   // body frame
@@ -1901,7 +1900,6 @@ typedef struct mjsBody_ {          // body specification
 } mjsBody;
 typedef struct mjsFrame_ {         // frame specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjString* childclass;            // childclass name
   double pos[3];                   // position
   double quat[4];                  // orientation
@@ -1910,7 +1908,6 @@ typedef struct mjsFrame_ {         // frame specification
 } mjsFrame;
 typedef struct mjsJoint_ {         // joint specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjtJoint type;                   // joint type
 
   // kinematics
@@ -1948,7 +1945,6 @@ typedef struct mjsJoint_ {         // joint specification
 } mjsJoint;
 typedef struct mjsGeom_ {          // geom specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjtGeom type;                    // geom type
 
   // frame, size
@@ -1994,7 +1990,6 @@ typedef struct mjsGeom_ {          // geom specification
 } mjsGeom;
 typedef struct mjsSite_ {          // site specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
 
   // frame, size
   double pos[3];                   // position
@@ -2015,7 +2010,6 @@ typedef struct mjsSite_ {          // site specification
 } mjsSite;
 typedef struct mjsCamera_ {        // camera specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
 
   // extrinsics
   double pos[3];                   // position
@@ -2042,7 +2036,6 @@ typedef struct mjsCamera_ {        // camera specification
 } mjsCamera;
 typedef struct mjsLight_ {         // light specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
 
   // frame
   double pos[3];                   // position
@@ -2070,7 +2063,6 @@ typedef struct mjsLight_ {         // light specification
 } mjsLight;
 typedef struct mjsFlex_ {          // flex specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
 
   // contact properties
   int contype;                     // contact type
@@ -2117,7 +2109,6 @@ typedef struct mjsFlex_ {          // flex specification
 } mjsFlex;
 typedef struct mjsMesh_ {          // mesh specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjString* content_type;          // content type of file
   mjString* file;                  // mesh file
   double refpos[3];                // reference position
@@ -2136,7 +2127,6 @@ typedef struct mjsMesh_ {          // mesh specification
 } mjsMesh;
 typedef struct mjsHField_ {        // height field specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjString* content_type;          // content type of file
   mjString* file;                  // file: (nrow, ncol, [elevation data])
   double size[4];                  // hfield size (ignore referencing geom size)
@@ -2147,7 +2137,6 @@ typedef struct mjsHField_ {        // height field specification
 } mjsHField;
 typedef struct mjsSkin_ {          // skin specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjString* file;                  // skin file
   mjString* material;              // name of material used for rendering
   float rgba[4];                   // rgba when material is omitted
@@ -2171,7 +2160,6 @@ typedef struct mjsSkin_ {          // skin specification
 } mjsSkin;
 typedef struct mjsTexture_ {       // texture specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjtTexture type;                 // texture type
   mjtColorSpace colorspace;        // colorspace
 
@@ -2207,7 +2195,6 @@ typedef struct mjsTexture_ {       // texture specification
 } mjsTexture;
 typedef struct mjsMaterial_ {      // material specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjStringVec* textures;           // names of textures (empty: none)
   mjtByte texuniform;              // make texture cube uniform
   float texrepeat[2];              // texture repetition for 2D mapping
@@ -2222,7 +2209,6 @@ typedef struct mjsMaterial_ {      // material specification
 } mjsMaterial;
 typedef struct mjsPair_ {          // pair specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjString* geomname1;             // name of geom 1
   mjString* geomname2;             // name of geom 2
 
@@ -2238,14 +2224,12 @@ typedef struct mjsPair_ {          // pair specification
 } mjsPair;
 typedef struct mjsExclude_ {       // exclude specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjString* bodyname1;             // name of geom 1
   mjString* bodyname2;             // name of geom 2
   mjString* info;                  // message appended to errors
 } mjsExclude;
 typedef struct mjsEquality_ {      // equality specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjtEq type;                      // constraint type
   double data[mjNEQDATA];          // type-dependent data
   mjtByte active;                  // is equality initially active
@@ -2258,7 +2242,6 @@ typedef struct mjsEquality_ {      // equality specification
 } mjsEquality;
 typedef struct mjsTendon_ {        // tendon specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
 
   // stiffness, damping, friction, armature
   double stiffness;                // stiffness coefficient
@@ -2294,7 +2277,6 @@ typedef struct mjsWrap_ {          // wrapping object specification
 } mjsWrap;
 typedef struct mjsActuator_ {      // actuator specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
 
   // gain, bias
   mjtGain gaintype;                // gain type
@@ -2334,7 +2316,6 @@ typedef struct mjsActuator_ {      // actuator specification
 } mjsActuator;
 typedef struct mjsSensor_ {        // sensor specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
 
   // sensor definition
   mjtSensor type;                  // type of sensor
@@ -2359,20 +2340,17 @@ typedef struct mjsSensor_ {        // sensor specification
 } mjsSensor;
 typedef struct mjsNumeric_ {       // custom numeric field specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjDoubleVec* data;               // initialization data
   int size;                        // array size, can be bigger than data size
   mjString* info;                  // message appended to compiler errors
 } mjsNumeric;
 typedef struct mjsText_ {          // custom text specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjString* data;                  // text string
   mjString* info;                  // message appended to compiler errors
 } mjsText;
 typedef struct mjsTuple_ {         // tuple specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjIntVec* objtype;               // object types
   mjStringVec* objname;            // object names
   mjDoubleVec* objprm;             // object parameters
@@ -2380,7 +2358,6 @@ typedef struct mjsTuple_ {         // tuple specification
 } mjsTuple;
 typedef struct mjsKey_ {           // keyframe specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   double time;                     // time
   mjDoubleVec* qpos;               // qpos
   mjDoubleVec* qvel;               // qvel
@@ -2392,7 +2369,6 @@ typedef struct mjsKey_ {           // keyframe specification
 } mjsKey;
 typedef struct mjsDefault_ {       // default specification
   mjsElement* element;             // element type
-  mjString* name;                  // class name
   mjsJoint* joint;                 // joint defaults
   mjsGeom* geom;                   // geom defaults
   mjsSite* site;                   // site defaults
@@ -3480,6 +3456,7 @@ mjsElement* mjs_firstChild(mjsBody* body, mjtObj type, int recurse);
 mjsElement* mjs_nextChild(mjsBody* body, mjsElement* child, int recurse);
 mjsElement* mjs_firstElement(mjSpec* s, mjtObj type);
 mjsElement* mjs_nextElement(mjSpec* s, mjsElement* element);
+void mjs_setName(mjsElement* element, const char* name);
 void mjs_setBuffer(mjByteVec* dest, const void* array, int size);
 void mjs_setString(mjString* dest, const char* text);
 void mjs_setStringVec(mjStringVec* dest, const char* text);
@@ -3491,6 +3468,7 @@ void mjs_setFloat(mjFloatVec* dest, const float* array, int size);
 void mjs_appendFloatVec(mjFloatVecVec* dest, const float* array, int size);
 void mjs_setDouble(mjDoubleVec* dest, const double* array, int size);
 void mjs_setPluginAttributes(mjsPlugin* plugin, void* attributes);
+mjString* mjs_getName(mjsElement* element);
 const char* mjs_getString(const mjString* source);
 const double* mjs_getDouble(const mjDoubleVec* source, int* size);
 const void* mjs_getPluginAttributes(const mjsPlugin* plugin);

include/mujoco/mjspec.h

@@ -205,7 +205,6 @@ typedef struct mjsPlugin_ {        // plugin specification
 
 typedef struct mjsBody_ {          // body specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjString* childclass;            // childclass name
 
   // body frame
@@ -233,7 +232,6 @@ typedef struct mjsBody_ {          // body specification
 
 typedef struct mjsFrame_ {         // frame specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjString* childclass;            // childclass name
   double pos[3];                   // position
   double quat[4];                  // orientation
@@ -244,7 +242,6 @@ typedef struct mjsFrame_ {         // frame specification
 
 typedef struct mjsJoint_ {         // joint specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjtJoint type;                   // joint type
 
   // kinematics
@@ -284,7 +281,6 @@ typedef struct mjsJoint_ {         // joint specification
 
 typedef struct mjsGeom_ {          // geom specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjtGeom type;                    // geom type
 
   // frame, size
@@ -332,7 +328,6 @@ typedef struct mjsGeom_ {          // geom specification
 
 typedef struct mjsSite_ {          // site specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
 
   // frame, size
   double pos[3];                   // position
@@ -355,7 +350,6 @@ typedef struct mjsSite_ {          // site specification
 
 typedef struct mjsCamera_ {        // camera specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
 
   // extrinsics
   double pos[3];                   // position
@@ -384,7 +378,6 @@ typedef struct mjsCamera_ {        // camera specification
 
 typedef struct mjsLight_ {         // light specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
 
   // frame
   double pos[3];                   // position
@@ -414,7 +407,6 @@ typedef struct mjsLight_ {         // light specification
 
 typedef struct mjsFlex_ {          // flex specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
 
   // contact properties
   int contype;                     // contact type
@@ -463,7 +455,6 @@ typedef struct mjsFlex_ {          // flex specification
 
 typedef struct mjsMesh_ {          // mesh specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjString* content_type;          // content type of file
   mjString* file;                  // mesh file
   double refpos[3];                // reference position
@@ -484,7 +475,6 @@ typedef struct mjsMesh_ {          // mesh specification
 
 typedef struct mjsHField_ {        // height field specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjString* content_type;          // content type of file
   mjString* file;                  // file: (nrow, ncol, [elevation data])
   double size[4];                  // hfield size (ignore referencing geom size)
@@ -498,7 +488,6 @@ typedef struct mjsHField_ {        // height field specification
 
 typedef struct mjsSkin_ {          // skin specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjString* file;                  // skin file
   mjString* material;              // name of material used for rendering
   float rgba[4];                   // rgba when material is omitted
@@ -524,7 +513,6 @@ typedef struct mjsSkin_ {          // skin specification
 
 typedef struct mjsTexture_ {       // texture specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjtTexture type;                 // texture type
   mjtColorSpace colorspace;        // colorspace
 
@@ -562,7 +550,6 @@ typedef struct mjsTexture_ {       // texture specification
 
 typedef struct mjsMaterial_ {      // material specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjStringVec* textures;           // names of textures (empty: none)
   mjtByte texuniform;              // make texture cube uniform
   float texrepeat[2];              // texture repetition for 2D mapping
@@ -579,7 +566,6 @@ typedef struct mjsMaterial_ {      // material specification
 
 typedef struct mjsPair_ {          // pair specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjString* geomname1;             // name of geom 1
   mjString* geomname2;             // name of geom 2
 
@@ -597,7 +583,6 @@ typedef struct mjsPair_ {          // pair specification
 
 typedef struct mjsExclude_ {       // exclude specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjString* bodyname1;             // name of geom 1
   mjString* bodyname2;             // name of geom 2
   mjString* info;                  // message appended to errors
@@ -606,7 +591,6 @@ typedef struct mjsExclude_ {       // exclude specification
 
 typedef struct mjsEquality_ {      // equality specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjtEq type;                      // constraint type
   double data[mjNEQDATA];          // type-dependent data
   mjtByte active;                  // is equality initially active
@@ -621,7 +605,6 @@ typedef struct mjsEquality_ {      // equality specification
 
 typedef struct mjsTendon_ {        // tendon specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
 
   // stiffness, damping, friction, armature
   double stiffness;                // stiffness coefficient
@@ -661,7 +644,6 @@ typedef struct mjsWrap_ {          // wrapping object specification
 
 typedef struct mjsActuator_ {      // actuator specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
 
   // gain, bias
   mjtGain gaintype;                // gain type
@@ -703,7 +685,6 @@ typedef struct mjsActuator_ {      // actuator specification
 
 typedef struct mjsSensor_ {        // sensor specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
 
   // sensor definition
   mjtSensor type;                  // type of sensor
@@ -730,7 +711,6 @@ typedef struct mjsSensor_ {        // sensor specification
 
 typedef struct mjsNumeric_ {       // custom numeric field specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjDoubleVec* data;               // initialization data
   int size;                        // array size, can be bigger than data size
   mjString* info;                  // message appended to compiler errors
@@ -739,7 +719,6 @@ typedef struct mjsNumeric_ {       // custom numeric field specification
 
 typedef struct mjsText_ {          // custom text specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjString* data;                  // text string
   mjString* info;                  // message appended to compiler errors
 } mjsText;
@@ -747,7 +726,6 @@ typedef struct mjsText_ {          // custom text specification
 
 typedef struct mjsTuple_ {         // tuple specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   mjIntVec* objtype;               // object types
   mjStringVec* objname;            // object names
   mjDoubleVec* objprm;             // object parameters
@@ -757,7 +735,6 @@ typedef struct mjsTuple_ {         // tuple specification
 
 typedef struct mjsKey_ {           // keyframe specification
   mjsElement* element;             // element type
-  mjString* name;                  // name
   double time;                     // time
   mjDoubleVec* qpos;               // qpos
   mjDoubleVec* qvel;               // qvel
@@ -771,7 +748,6 @@ typedef struct mjsKey_ {           // keyframe specification
 
 typedef struct mjsDefault_ {       // default specification
   mjsElement* element;             // element type
-  mjString* name;                  // class name
   mjsJoint* joint;                 // joint defaults
   mjsGeom* geom;                   // geom defaults
   mjsSite* site;                   // site defaults

include/mujoco/mujoco.h

@@ -1600,6 +1600,9 @@ MJAPI mjsElement* mjs_nextElement(mjSpec* s, mjsElement* element);
 
 //---------------------------------- Attribute setters ---------------------------------------------
 
+// Set element's name.
+MJAPI void mjs_setName(mjsElement* element, const char* name);
+
 // Copy buffer.
 MJAPI void mjs_setBuffer(mjByteVec* dest, const void* array, int size);
 
@@ -1636,6 +1639,9 @@ MJAPI void mjs_setPluginAttributes(mjsPlugin* plugin, void* attributes);
 
 //---------------------------------- Attribute getters ---------------------------------------------
 
+// Get element's name.
+MJAPI mjString* mjs_getName(mjsElement* element);
+
 // Get string contents.
 MJAPI const char* mjs_getString(const mjString* source);
 

python/mujoco/codegen/generate_spec_bindings.py

@@ -341,9 +341,14 @@ def generate_add() -> None:
       else:
         return '', '', ''
 
-    code_field = ''
-    set_types = []
-    names = []
+    if key == 'mjsPlugin':
+      code_field = ''
+      set_types = []
+      names = []
+    else:
+      code_field = 'set_name("name", out->element);'
+      set_types = ['name']
+      names = ['name']
     for field in structs.STRUCTS[key].fields:
       line, set_type, name = _field(field)
       if line:
@@ -571,6 +576,21 @@ def generate_add() -> None:
             }
           };
           """
+        elif t == 'name':
+          code += """\n
+          auto set_name = [&kwargs](const char* str, raw::MjsElement* el) {
+            if (kwargs.contains(str)) {
+              try {
+                std::string name = kwargs[str].cast<std::string>();
+                mjs_setName(el, name.c_str());
+              } catch (const py::cast_error &e) {
+                throw pybind11::value_error(std::string(str) + " should be a string.");
+              }
+            }
+          };
+          """
+        else:
+          raise NotImplementedError(f'Unsupported set type: {t} in {key}')
 
     code += code_field
     code += f"""\n
@@ -644,6 +664,25 @@ def generate_id() -> None:
     print(code)
 
 
+def generate_name() -> None:
+  """Generate name functions."""
+  for key, _, _, _, _ in SPECS + [('mjsDefault', '', '', '', '')]:
+    if key == 'mjsPlugin':
+      continue
+    elem = key.removeprefix('mjs')
+    titlecase = 'Mjs' + elem
+    code = f"""\n
+      {key}.def_property("name",
+      [](raw::{titlecase}& self) -> std::string* {{
+        return mjs_getName(self.element);
+      }},
+      [](raw::{titlecase}& self, std::string& name) -> void {{
+        mjs_setName(self.element, name.c_str());
+      }}, py::return_value_policy::reference_internal);
+    """
+    print(code)
+
+
 def main(argv: Sequence[str]) -> None:
   if len(argv) > 1:
     raise app.UsageError('Too many command-line arguments.')
@@ -652,6 +691,7 @@ def main(argv: Sequence[str]) -> None:
   generate_find()
   generate_signature()
   generate_id()
+  generate_name()
 
 
 if __name__ == '__main__':

python/mujoco/introspect/functions.py

@@ -10191,6 +10191,26 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
          ),
          doc="Return spec's next element; return NULL if element is last.",
      )),
+    ('mjs_setName',
+     FunctionDecl(
+         name='mjs_setName',
+         return_type=ValueType(name='void'),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+             FunctionParameterDecl(
+                 name='name',
+                 type=PointerType(
+                     inner_type=ValueType(name='char', is_const=True),
+                 ),
+             ),
+         ),
+         doc="Set element's name.",
+     )),
     ('mjs_setBuffer',
      FunctionDecl(
          name='mjs_setBuffer',
@@ -10439,6 +10459,22 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
          ),
          doc='Set plugin attributes.',
      )),
+    ('mjs_getName',
+     FunctionDecl(
+         name='mjs_getName',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjString'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc="Get element's name.",
+     )),
     ('mjs_getString',
      FunctionDecl(
          name='mjs_getString',

python/mujoco/introspect/structs.py

@@ -8222,13 +8222,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='childclass',
                  type=PointerType(
@@ -8347,13 +8340,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='childclass',
                  type=PointerType(
@@ -8403,13 +8389,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='type',
                  type=ValueType(name='mjtJoint'),
@@ -8575,13 +8554,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='type',
                  type=ValueType(name='mjtGeom'),
@@ -8783,13 +8755,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='pos',
                  type=ArrayType(
@@ -8880,13 +8845,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='pos',
                  type=ArrayType(
@@ -9019,13 +8977,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='pos',
                  type=ArrayType(
@@ -9154,13 +9105,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='contype',
                  type=ValueType(name='int'),
@@ -9380,13 +9324,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='content_type',
                  type=PointerType(
@@ -9501,13 +9438,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='content_type',
                  type=PointerType(
@@ -9568,13 +9498,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='file',
                  type=PointerType(
@@ -9684,13 +9607,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='type',
                  type=ValueType(name='mjtTexture'),
@@ -9830,13 +9746,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='textures',
                  type=PointerType(
@@ -9916,13 +9825,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='geomname1',
                  type=PointerType(
@@ -10005,13 +9907,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='bodyname1',
                  type=PointerType(
@@ -10047,13 +9942,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='type',
                  type=ValueType(name='mjtEq'),
@@ -10128,13 +10016,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='stiffness',
                  type=ValueType(name='double'),
@@ -10300,13 +10181,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='gaintype',
                  type=ValueType(name='mjtGain'),
@@ -10485,13 +10359,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='type',
                  type=ValueType(name='mjtSensor'),
@@ -10579,13 +10446,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='data',
                  type=PointerType(
@@ -10619,13 +10479,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='data',
                  type=PointerType(
@@ -10654,13 +10507,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='objtype',
                  type=PointerType(
@@ -10703,13 +10549,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='name',
-             ),
              StructFieldDecl(
                  name='time',
                  type=ValueType(name='double'),
@@ -10778,13 +10617,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='element type',
              ),
-             StructFieldDecl(
-                 name='name',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjString'),
-                 ),
-                 doc='class name',
-             ),
              StructFieldDecl(
                  name='joint',
                  type=PointerType(

python/mujoco/specs.cc

@@ -521,7 +521,8 @@ PYBIND11_MODULE(_specs, m) {
             }
           } else if (key == "name") {
             try {
-              *out->name = kwargs["name"].cast<std::string>();
+              mjs_setName(out->element,
+                          kwargs["name"].cast<std::string>().c_str());
             } catch (const py::cast_error& e) {
               throw pybind11::value_error("name is the wrong type.");
             }
@@ -552,7 +553,8 @@ PYBIND11_MODULE(_specs, m) {
       },
       [](raw::MjsBody& self, raw::MjsDefault& default_) -> void {
         mjs_setDefault(self.element, &default_);
-      });
+      },
+      py::return_value_policy::reference_internal);
   mjsBody.def(
       "find_all",
       [](raw::MjsBody& self, mjtObj objtype) -> py::list {
@@ -819,7 +821,8 @@ PYBIND11_MODULE(_specs, m) {
       },
       [](raw::MjsGeom& self, raw::MjsDefault& default_) -> void {
         mjs_setDefault(self.element, &default_);
-      });
+      },
+      py::return_value_policy::reference_internal);
   mjsGeom.def_property_readonly(
       "frame",
       [](raw::MjsGeom& self) -> raw::MjsFrame* {
@@ -849,7 +852,8 @@ PYBIND11_MODULE(_specs, m) {
       },
       [](raw::MjsJoint& self, raw::MjsDefault& default_) -> void {
         mjs_setDefault(self.element, &default_);
-      });
+      },
+      py::return_value_policy::reference_internal);
   mjsJoint.def_property_readonly(
       "frame",
       [](raw::MjsJoint& self) -> raw::MjsFrame* {
@@ -879,7 +883,8 @@ PYBIND11_MODULE(_specs, m) {
       },
       [](raw::MjsSite& self, raw::MjsDefault& default_) -> void {
         mjs_setDefault(self.element, &default_);
-      });
+      },
+      py::return_value_policy::reference_internal);
   mjsSite.def(
       "attach_body",
       [](raw::MjsSite& self, raw::MjsBody& body,
@@ -926,7 +931,8 @@ PYBIND11_MODULE(_specs, m) {
       },
       [](raw::MjsCamera& self, raw::MjsDefault& default_) -> void {
         mjs_setDefault(self.element, &default_);
-      });
+      },
+      py::return_value_policy::reference_internal);
   mjsCamera.def_property_readonly(
       "frame",
       [](raw::MjsCamera& self) -> raw::MjsFrame* {
@@ -956,7 +962,8 @@ PYBIND11_MODULE(_specs, m) {
       },
       [](raw::MjsLight& self, raw::MjsDefault& default_) -> void {
         mjs_setDefault(self.element, &default_);
-      });
+      },
+      py::return_value_policy::reference_internal);
   mjsLight.def_property_readonly(
       "frame",
       [](raw::MjsLight& self) -> raw::MjsFrame* {
@@ -975,7 +982,8 @@ PYBIND11_MODULE(_specs, m) {
       },
       [](raw::MjsMaterial& self, raw::MjsDefault& default_) -> void {
         mjs_setDefault(self.element, &default_);
-      });
+      },
+      py::return_value_policy::reference_internal);
 
   // ============================= MJSMESH =====================================
   mjSpec.def("delete", [](MjSpec& self, raw::MjsMesh& obj) {
@@ -988,7 +996,8 @@ PYBIND11_MODULE(_specs, m) {
       },
       [](raw::MjsMesh& self, raw::MjsDefault& default_) -> void {
         mjs_setDefault(self.element, &default_);
-      });
+      },
+      py::return_value_policy::reference_internal);
 
   // ============================= MJSPAIR =====================================
   mjSpec.def("delete", [](MjSpec& self, raw::MjsPair& obj) {
@@ -1001,7 +1010,8 @@ PYBIND11_MODULE(_specs, m) {
       },
       [](raw::MjsPair& self, raw::MjsDefault& default_) -> void {
         mjs_setDefault(self.element, &default_);
-      });
+      },
+      py::return_value_policy::reference_internal);
 
   // ============================= MJSEQUAL ====================================
   mjSpec.def("delete", [](MjSpec& self, raw::MjsEquality& obj) {
@@ -1014,7 +1024,8 @@ PYBIND11_MODULE(_specs, m) {
       },
       [](raw::MjsEquality& self, raw::MjsDefault& default_) -> void {
         mjs_setDefault(self.element, &default_);
-      });
+      },
+      py::return_value_policy::reference_internal);
 
   // ============================= MJSACTUATOR =================================
   mjSpec.def("delete", [](MjSpec& self, raw::MjsActuator& obj) {
@@ -1027,7 +1038,8 @@ PYBIND11_MODULE(_specs, m) {
       },
       [](raw::MjsActuator& self, raw::MjsDefault& default_) -> void {
         mjs_setDefault(self.element, &default_);
-      });
+      },
+      py::return_value_policy::reference_internal);
   mjsActuator.def("set_to_motor", [](raw::MjsActuator* self) {
     std::string err = mjs_setToMotor(self);
     if (!err.empty()) {

src/experimental/usd/plugins/mjcf/mujoco_to_usd.cc

@@ -334,14 +334,14 @@ class ModelWriter {
   }
 
   void WriteMesh(const mjsMesh *mesh, const pxr::SdfPath &parent_path) {
-    auto name = GetAvailablePrimName(*mesh->name, pxr::UsdGeomTokens->Mesh,
+    auto name = GetAvailablePrimName(*mjs_getName(mesh->element), pxr::UsdGeomTokens->Mesh,
                                      parent_path);
     pxr::SdfPath subcomponent_path =
         CreatePrimSpec(data_, parent_path, name, pxr::UsdGeomTokens->Xform);
     pxr::SdfPath mesh_path =
         CreatePrimSpec(data_, subcomponent_path, kTokens->sourceMesh,
                        pxr::UsdGeomTokens->Mesh);
-    mesh_paths_[*mesh->name] = subcomponent_path;
+    mesh_paths_[*mjs_getName(mesh->element)] = subcomponent_path;
 
     if (write_physics_) {
       ApplyApiSchema(data_, mesh_path, MjcPhysicsTokens->MeshCollisionAPI);
@@ -725,8 +725,9 @@ class ModelWriter {
 
   void WriteMaterial(mjsMaterial *material, const pxr::SdfPath &parent_path) {
     // Create a Material prim.
-    auto name = GetAvailablePrimName(
-        *material->name, pxr::UsdShadeTokens->Material, parent_path);
+    auto name =
+        GetAvailablePrimName(*mjs_getName(material->element),
+                             pxr::UsdShadeTokens->Material, parent_path);
     pxr::SdfPath material_path =
         CreatePrimSpec(data_, parent_path, name, pxr::UsdShadeTokens->Material);
 
@@ -1008,9 +1009,9 @@ class ModelWriter {
     std::unordered_map<std::string, std::vector<mjsKey *>> keyframes_map;
     mjsKey *keyframe = mjs_asKey(mjs_firstElement(spec_, mjOBJ_KEY));
     while (keyframe) {
-      std::string keyframe_name = keyframe->name->empty()
+      std::string keyframe_name = mjs_getName(keyframe->element)->empty()
                                       ? MjcPhysicsTokens->Keyframe
-                                      : *keyframe->name;
+                                      : *mjs_getName(keyframe->element);
       keyframes_map[keyframe_name].push_back(keyframe);
       keyframe = mjs_asKey(mjs_nextElement(spec_, keyframe->element));
     }
@@ -1174,7 +1175,9 @@ class ModelWriter {
 
   pxr::SdfPath WriteMeshGeom(const mjsGeom *geom,
                              const pxr::SdfPath &body_path) {
-    std::string mj_name = geom->name->empty() ? *geom->meshname : *geom->name;
+    std::string mj_name = mjs_getName(geom->element)->empty()
+                              ? *geom->meshname
+                              : *mjs_getName(geom->element);
     auto name =
         GetAvailablePrimName(mj_name, pxr::UsdGeomTokens->Mesh, body_path);
     pxr::SdfPath subcomponent_path =
@@ -1196,8 +1199,8 @@ class ModelWriter {
 
   pxr::SdfPath WriteSiteGeom(const mjsSite *site,
                              const pxr::SdfPath &body_path) {
-    auto name =
-        GetAvailablePrimName(*site->name, pxr::UsdGeomTokens->Cube, body_path);
+    auto name = GetAvailablePrimName(*mjs_getName(site->element),
+                                     pxr::UsdGeomTokens->Cube, body_path);
 
     int site_idx = mjs_getId(site->element);
     const mjtNum *size = &model_->site_size[site_idx * 3];
@@ -1254,8 +1257,8 @@ class ModelWriter {
 
   pxr::SdfPath WriteBoxGeom(const mjsGeom *geom,
                             const pxr::SdfPath &body_path) {
-    auto name =
-        GetAvailablePrimName(*geom->name, pxr::UsdGeomTokens->Cube, body_path);
+    auto name = GetAvailablePrimName(*mjs_getName(geom->element),
+                                     pxr::UsdGeomTokens->Cube, body_path);
 
     int geom_idx = mjs_getId(geom->element);
     mjtNum *geom_size = &model_->geom_size[geom_idx * 3];
@@ -1282,8 +1285,8 @@ class ModelWriter {
 
   pxr::SdfPath WriteCapsuleGeom(const mjsGeom *geom,
                                 const pxr::SdfPath &body_path) {
-    auto name = GetAvailablePrimName(*geom->name, pxr::UsdGeomTokens->Capsule,
-                                     body_path);
+    auto name = GetAvailablePrimName(*mjs_getName(geom->element),
+                                     pxr::UsdGeomTokens->Capsule, body_path);
     int geom_idx = mjs_getId(geom->element);
     mjtNum *geom_size = &model_->geom_size[geom_idx * 3];
 
@@ -1310,8 +1313,8 @@ class ModelWriter {
 
   pxr::SdfPath WriteCylinderGeom(const mjsGeom *geom,
                                  const pxr::SdfPath &body_path) {
-    auto name = GetAvailablePrimName(*geom->name, pxr::UsdGeomTokens->Cylinder,
-                                     body_path);
+    auto name = GetAvailablePrimName(*mjs_getName(geom->element),
+                                     pxr::UsdGeomTokens->Cylinder, body_path);
 
     int geom_idx = mjs_getId(geom->element);
     mjtNum *geom_size = &model_->geom_size[geom_idx * 3];
@@ -1340,8 +1343,8 @@ class ModelWriter {
 
   pxr::SdfPath WriteEllipsoidGeom(const mjsGeom *geom,
                                   const pxr::SdfPath &body_path) {
-    auto name = GetAvailablePrimName(*geom->name, pxr::UsdGeomTokens->Sphere,
-                                     body_path);
+    auto name = GetAvailablePrimName(*mjs_getName(geom->element),
+                                     pxr::UsdGeomTokens->Sphere, body_path);
     int geom_idx = mjs_getId(geom->element);
     mjtNum *geom_size = &model_->geom_size[geom_idx * 3];
 
@@ -1362,8 +1365,8 @@ class ModelWriter {
 
   pxr::SdfPath WriteSphereGeom(const mjsGeom *geom,
                                const pxr::SdfPath &body_path) {
-    auto name = GetAvailablePrimName(*geom->name, pxr::UsdGeomTokens->Sphere,
-                                     body_path);
+    auto name = GetAvailablePrimName(*mjs_getName(geom->element),
+                                     pxr::UsdGeomTokens->Sphere, body_path);
     int geom_idx = mjs_getId(geom->element);
     mjtNum *geom_size = &model_->geom_size[geom_idx * 3];
     return WriteSphere(name, geom_size, body_path);
@@ -1399,8 +1402,8 @@ class ModelWriter {
 
   pxr::SdfPath WritePlaneGeom(const mjsGeom *geom,
                               const pxr::SdfPath &body_path) {
-    auto name =
-        GetAvailablePrimName(*geom->name, pxr::UsdGeomTokens->Plane, body_path);
+    auto name = GetAvailablePrimName(*mjs_getName(geom->element),
+                                     pxr::UsdGeomTokens->Plane, body_path);
     int geom_idx = mjs_getId(geom->element);
     mjtNum *geom_size = &model_->geom_size[geom_idx * 3];
     return WritePlane(name, geom_size, body_path);
@@ -1409,8 +1412,8 @@ class ModelWriter {
   void WriteSite(mjsSite *site, const mjsBody *body) {
     const int body_id = mjs_getId(body->element);
     const auto &body_path = body_paths_[body_id];
-    auto name =
-        GetAvailablePrimName(*site->name, pxr::UsdGeomTokens->Xform, body_path);
+    auto name = GetAvailablePrimName(*mjs_getName(site->element),
+                                     pxr::UsdGeomTokens->Xform, body_path);
 
     // Create a geom primitive and set its purpose to guide so it won't be
     // rendered.
@@ -1519,7 +1522,8 @@ class ModelWriter {
     }
 
     mjsDefault *spec_default = mjs_getDefault(geom->element);
-    pxr::TfToken valid_class_name = GetValidPrimName(*spec_default->name);
+    pxr::TfToken valid_class_name =
+        GetValidPrimName(*mjs_getName(spec_default->element));
     pxr::SdfPath geom_class_path = class_path_.AppendChild(valid_class_name);
     if (!data_->HasSpec(geom_class_path)) {
       pxr::SdfPath class_path =
@@ -1645,7 +1649,7 @@ class ModelWriter {
           break;
         default:
           TF_WARN("Unsupported joint type '%d' for joint '%s'. Skipping.",
-                  (int)type, joint->name->c_str());
+                  (int)type, mjs_getName(joint->element)->c_str());
           return;
       }
     }
@@ -1658,7 +1662,7 @@ class ModelWriter {
     int body0_id_usd = model_->body_parentid[body_id];
 
     const pxr::SdfPath &body1_path_usd = body_paths_[body1_id_usd];
-    auto joint_name = joint ? *joint->name : "FixedJoint";
+    auto joint_name = joint ? *mjs_getName(joint->element) : "FixedJoint";
     pxr::TfToken joint_name_token =
         GetAvailablePrimName(joint_name, kTokens->joint, body1_path_usd);
     pxr::SdfPath joint_path = CreatePrimSpec(data_, body1_path_usd,
@@ -1892,7 +1896,7 @@ class ModelWriter {
 
   void WriteCamera(mjsCamera *spec_cam, const mjsBody *body) {
     const auto &body_path = body_paths_[mjs_getId(body->element)];
-    auto name = GetAvailablePrimName(*spec_cam->name,
+    auto name = GetAvailablePrimName(*mjs_getName(spec_cam->element),
                                      pxr::UsdGeomTokens->Camera, body_path);
     // Create a root Xform for the world body with the model name if it exists
     // otherwise called 'World'.
@@ -1950,7 +1954,8 @@ class ModelWriter {
 
   void WriteLight(mjsLight *light, const mjsBody *body) {
     const auto &body_path = body_paths_[mjs_getId(body->element)];
-    auto name = GetAvailablePrimName(*light->name, kTokens->light, body_path);
+    auto name = GetAvailablePrimName(*mjs_getName(light->element),
+                                     kTokens->light, body_path);
     // Create a root Xform for the world body with the model name if it exists
     // otherwise called 'World'.
     pxr::SdfPath light_path =
@@ -1978,7 +1983,7 @@ class ModelWriter {
     mjsBody *parent = mjs_getParent(body->element);
     int parent_id = mjs_getId(parent->element);
     pxr::SdfPath parent_path = body_paths_[parent_id];
-    pxr::TfToken body_name = GetValidPrimName(*body->name);
+    pxr::TfToken body_name = GetValidPrimName(*mjs_getName(body->element));
 
     // Create Xform prim for body.
     pxr::SdfPath body_path = CreatePrimSpec(data_, parent_path, body_name,
@@ -2046,7 +2051,8 @@ class ModelWriter {
     // Create classes if necessary
     mjsDefault *spec_default = mjs_getDefault(body->element);
 
-    pxr::TfToken body_class_name = GetValidPrimName(*spec_default->name);
+    pxr::TfToken body_class_name =
+        GetValidPrimName(*mjs_getName(spec_default->element));
     pxr::SdfPath body_class_path = class_path_.AppendChild(body_class_name);
     if (!data_->HasSpec(body_class_path)) {
       CreateClassSpec(data_, class_path_, body_class_name);
@@ -2069,7 +2075,7 @@ class ModelWriter {
                       pxr::VtArray<pxr::TfToken>{kTokens->xformOpTransform});
 
     pxr::VtDictionary customData;
-    customData[kTokens->body_name] = *body->name;
+    customData[kTokens->body_name] = *mjs_getName(body->element);
     SetPrimMetadata(data_, body_path, pxr::SdfFieldKeys->CustomData,
                     customData);
 

src/experimental/usd/usd_to_mjspec.cc

@@ -556,7 +556,7 @@ void ParseMjcPhysicsGeneralActuatorAPI(mjSpec* spec,
                                        const std::string* name) {
   pxr::UsdPrim prim = act.GetPrim();
   mjsActuator* mj_act = mjs_addActuator(spec, nullptr);
-  mjs_setString(mj_act->name, prim.GetPath().GetAsString().c_str());
+  mjs_setName(mj_act->element, prim.GetPath().GetAsString().c_str());
   mjs_setString(mj_act->target, name->c_str());
   mj_act->trntype = tran_type;
 
@@ -732,7 +732,7 @@ void ParseMjcPhysicsJointAPI(mjsJoint* mj_joint,
       mju_warning(
           "springdamper attribute for joint %s has incorrect size %zu, "
           "expected 2.",
-          mj_joint->name->c_str(), springdamper.size());
+          mjs_getName(mj_joint->element)->c_str(), springdamper.size());
     }
   }
 
@@ -748,7 +748,7 @@ void ParseMjcPhysicsJointAPI(mjsJoint* mj_joint,
       mju_warning(
           "solreflimit attribute for joint %s has incorrect size %zu, "
           "expected %d.",
-          mj_joint->name->c_str(), solreflimit.size(), mjNREF);
+          mjs_getName(mj_joint->element)->c_str(), solreflimit.size(), mjNREF);
     }
   }
 
@@ -764,7 +764,7 @@ void ParseMjcPhysicsJointAPI(mjsJoint* mj_joint,
       mju_warning(
           "solimplimit attribute for joint %s has incorrect size %zu, "
           "expected %d.",
-          mj_joint->name->c_str(), solimplimit.size(), mjNIMP);
+          mjs_getName(mj_joint->element)->c_str(), solimplimit.size(), mjNIMP);
     }
   }
 
@@ -780,7 +780,8 @@ void ParseMjcPhysicsJointAPI(mjsJoint* mj_joint,
       mju_warning(
           "solreffriction attribute for joint %s has incorrect size %zu, "
           "expected %d.",
-          mj_joint->name->c_str(), solreffriction.size(), mjNREF);
+          mjs_getName(mj_joint->element)->c_str(), solreffriction.size(),
+          mjNREF);
     }
   }
 
@@ -796,7 +797,8 @@ void ParseMjcPhysicsJointAPI(mjsJoint* mj_joint,
       mju_warning(
           "solimpfriction attribute for joint %s has incorrect size %zu, "
           "expected %d.",
-          mj_joint->name->c_str(), solimpfriction.size(), mjNIMP);
+          mjs_getName(mj_joint->element)->c_str(), solimpfriction.size(),
+          mjNIMP);
     }
   }
 
@@ -898,7 +900,7 @@ void ParseUsdPhysicsCollider(mjSpec* spec,
   }
 
   mjsGeom* geom = mjs_addGeom(parent, nullptr);
-  mjs_setString(geom->name, prim.GetPath().GetAsString().c_str());
+  mjs_setName(geom->element, prim.GetPath().GetAsString().c_str());
   geom->contype = 1;
   geom->conaffinity = 1;
 
@@ -983,7 +985,7 @@ void ParseUsdPhysicsCollider(mjSpec* spec,
       }
 
       std::string mesh_name = usd_mesh.GetPath().GetAsString();
-      mjs_setString(mesh->name, mesh_name.c_str());
+      mjs_setName(mesh->element, mesh_name.c_str());
       mjs_setFloat(mesh->uservert, uservert.data(), uservert.size());
       mjs_setInt(mesh->userface, userface.data(), userface.size());
 
@@ -1047,7 +1049,7 @@ void ParseUsdPhysicsJoint(mjSpec* spec, const pxr::UsdPrim& prim, mjsBody* body,
 
   mjsJoint* mj_joint = mjs_addJoint(body, nullptr);
   mj_joint->type = type;
-  mjs_setString(mj_joint->name, prim.GetPath().GetAsString().c_str());
+  mjs_setName(mj_joint->element, prim.GetPath().GetAsString().c_str());
 
   if (prim.IsA<pxr::UsdPhysicsRevoluteJoint>()) {
     pxr::UsdPhysicsRevoluteJoint revolute(prim);
@@ -1123,7 +1125,8 @@ void ParseUsdPhysicsJoint(mjSpec* spec, const pxr::UsdPrim& prim, mjsBody* body,
 
   if (prim.HasAPI<pxr::MjcPhysicsActuatorAPI>()) {
     ParseMjcPhysicsGeneralActuatorAPI(spec, pxr::MjcPhysicsActuatorAPI(prim),
-                                      mjtTrn::mjTRN_JOINT, mj_joint->name);
+                                      mjtTrn::mjTRN_JOINT,
+                                      mjs_getName(mj_joint->element));
   }
 
   if (prim.HasAPI<pxr::MjcPhysicsJointAPI>()) {
@@ -1136,7 +1139,7 @@ void ParseMjcPhysicsSite(mjSpec* spec, const pxr::MjcPhysicsSiteAPI& site_api,
                          pxr::UsdGeomXformCache& xform_cache) {
   auto prim = site_api.GetPrim();
   mjsSite* site = mjs_addSite(parent, 0);
-  mjs_setString(site->name, site_api.GetPrim().GetPath().GetAsString().c_str());
+  mjs_setName(site->element, site_api.GetPrim().GetPath().GetAsString().c_str());
   SetLocalPoseFromPrim(site_api.GetPrim(), parent_prim, site, xform_cache);
 
   // Convert USD type to MuJoCo type.
@@ -1152,7 +1155,7 @@ void ParseMjcPhysicsSite(mjSpec* spec, const pxr::MjcPhysicsSiteAPI& site_api,
     ParseMjcPhysicsGeneralActuatorAPI(
         spec, pxr::MjcPhysicsActuatorAPI(prim),
         slider_crank ? mjtTrn::mjTRN_SLIDERCRANK : mjtTrn::mjTRN_SITE,
-        site->name);
+        mjs_getName(site->element));
   }
 }
 
@@ -1187,7 +1190,7 @@ void ParseMjcPhysicsKeyframe(mjSpec* spec,
   if (n_time_samples == 0) {
     // If no time samples, we create a single keyframe.
     mjsKey* key = mjs_addKey(spec);
-    mjs_setString(key->name, prim.GetName().GetString().c_str());
+    mjs_setName(key->element, prim.GetName().GetString().c_str());
     setKeyframeData(key, qpos_attr, &key->qpos);
     setKeyframeData(key, qvel_attr, &key->qvel);
     setKeyframeData(key, act_attr, &key->act);
@@ -1203,7 +1206,7 @@ void ParseMjcPhysicsKeyframe(mjSpec* spec,
       mjsKey* key = mjs_addKey(spec);
       std::string key_name =
           prim.GetName().GetString() + "_" + std::to_string(keyframe_id++);
-      mjs_setString(key->name, key_name.c_str());
+      mjs_setName(key->element, key_name.c_str());
       key->time = time;
       setKeyframeData(key, qpos_attr, &key->qpos, &time);
       setKeyframeData(key, qvel_attr, &key->qvel, &time);
@@ -1221,7 +1224,7 @@ mjsBody* ParseUsdPhysicsRigidbody(
     pxr::UsdGeomXformCache& xform_cache) {
   pxr::UsdPrim prim = rigidbody_api.GetPrim();
   mjsBody* body = mjs_addBody(parent, nullptr);
-  mjs_setString(body->name, prim.GetPath().GetAsString().c_str());
+  mjs_setName(body->element, prim.GetPath().GetAsString().c_str());
   SetLocalPoseFromPrim(prim, parent_prim, body, xform_cache);
 
   if (prim.HasAPI<pxr::UsdPhysicsMassAPI>()) {
@@ -1230,7 +1233,8 @@ mjsBody* ParseUsdPhysicsRigidbody(
 
   if (prim.HasAPI<pxr::MjcPhysicsActuatorAPI>()) {
     ParseMjcPhysicsGeneralActuatorAPI(spec, pxr::MjcPhysicsActuatorAPI(prim),
-                                      mjtTrn::mjTRN_BODY, body->name);
+                                      mjtTrn::mjTRN_BODY,
+                                      mjs_getName(body->element));
   }
 
   mujoco::usd::SetUsdPrimPathUserValue(body->element, prim.GetPath());

src/user/user_api.cc

@@ -1341,6 +1341,19 @@ mjsPlugin* mjs_asPlugin(mjsElement* element) {
 
 
 
+// set element name
+void mjs_setName(mjsElement* element, const char* name) {
+  if (element->elemtype == mjOBJ_DEFAULT) {
+    mjCDef* def = static_cast<mjCDef*>(element);
+    def->name = std::string(name);
+    return;
+  }
+  mjCBase* baseC = static_cast<mjCBase*>(element);
+  baseC->name = std::string(name);
+}
+
+
+
 // copy buffer to destination buffer
 void mjs_setBuffer(mjByteVec* dest, const void* array, int size) {
   const std::byte* buffer = static_cast<const std::byte*>(array);
@@ -1430,6 +1443,16 @@ void mjs_setDouble(mjDoubleVec* dest, const double* array, int size) {
 
 
 
+// get name
+mjString* mjs_getName(mjsElement* element) {
+  if (element->elemtype == mjOBJ_DEFAULT) {
+    return &(static_cast<mjCDef*>(element)->name);
+  }
+  return &(static_cast<mjCBase*>(element)->name);
+}
+
+
+
 // get string
 const char* mjs_getString(const mjString* source) {
   return source->c_str();

src/user/user_api.h

@@ -339,6 +339,9 @@ MJAPI mjsPlugin* mjs_asPlugin(mjsElement* element);
 
 //---------------------------------- Attribute setters ---------------------------------------------
 
+// Set element's name.
+MJAPI void mjs_setName(mjsElement* element, const char* name);
+
 // Copy buffer.
 MJAPI void mjs_setBuffer(mjByteVec* dest, const void* array, int size);
 
@@ -375,6 +378,9 @@ MJAPI void mjs_setPluginAttributes(mjsPlugin* plugin, void* attributes);
 
 //---------------------------------- Attribute getters ---------------------------------------------
 
+// Get element's name.
+MJAPI mjString* mjs_getName(mjsElement* element);
+
 // Get string contents.
 MJAPI const char* mjs_getString(const mjString* source);
 

src/user/user_composite.cc

@@ -255,7 +255,7 @@ bool mjCComposite::MakeCable(mjCModel* model, mjsBody* body, char* error, int er
 
   // add name to model
   mjsText* pte = mjs_addText(&model->spec);
-  mjs_setString(pte->name, ("composite_" + prefix).c_str());
+  mjs_setName(pte->element, ("composite_" + prefix).c_str());
   mjs_setString(pte->data, ("rope_" + prefix).c_str());
 
   // populate uservert if not specified
@@ -372,7 +372,7 @@ mjsBody* mjCComposite::AddCableBody(mjCModel* model, mjsBody* body, int ix,
 
   // add body
   body = mjs_addBody(body, 0);
-  mjs_setString(body->name, this_body);
+  mjs_setName(body->element, this_body);
   if (first) {
     mjuu_setvec(body->pos, offset[0]+uservert[3*ix],
                            offset[1]+uservert[3*ix+1],
@@ -391,7 +391,7 @@ mjsBody* mjCComposite::AddCableBody(mjCModel* model, mjsBody* body, int ix,
   // add geom
   mjsGeom* geom = mjs_addGeom(body, &def[0].spec);
   mjs_setDefault(geom->element, mjs_getDefault(body->element));
-  mjs_setString(geom->name, txt_geom);
+  mjs_setName(geom->element, txt_geom);
   if (def[0].spec.geom->type == mjGEOM_CYLINDER ||
       def[0].spec.geom->type == mjGEOM_CAPSULE) {
     mjuu_zerovec(geom->fromto, 6);
@@ -422,7 +422,7 @@ mjsBody* mjCComposite::AddCableBody(mjCModel* model, mjsBody* body, int ix,
     jnt->damping = jnt->type == mjJNT_FREE ? 0 : jnt->damping;
     jnt->armature = jnt->type == mjJNT_FREE ? 0 : jnt->armature;
     jnt->frictionloss = jnt->type == mjJNT_FREE ? 0 : jnt->frictionloss;
-    mjs_setString(jnt->name, this_joint);
+    mjs_setName(jnt->element, this_joint);
   }
 
   // exclude contact pair
@@ -436,7 +436,7 @@ mjsBody* mjCComposite::AddCableBody(mjCModel* model, mjsBody* body, int ix,
   if (last || first) {
     mjsSite* site = mjs_addSite(body, &def[0].spec);
     mjs_setDefault(site->element, mjs_getDefault(body->element));
-    mjs_setString(site->name, txt_site);
+    mjs_setName(site->element, txt_site);
     mjuu_setvec(site->pos, last ? length : 0, 0, 0);
     mjuu_setvec(site->quat, 1, 0, 0, 0);
   }
@@ -480,7 +480,7 @@ void mjCComposite::MakeSkin2(mjCModel* model, mjtNum inflate) {
   // add skin, set name and material
   mjsSkin* skin = mjs_addSkin(&model->spec);
   mju::sprintf_arr(txt, "%sSkin", prefix.c_str());
-  mjs_setString(skin->name, txt);
+  mjs_setName(skin->element, txt);
   mjs_setString(skin->material, skinmaterial.c_str());
   mjuu_copyvec(skin->rgba, skinrgba, 4);
   skin->inflate = inflate;
@@ -967,7 +967,7 @@ void mjCComposite::MakeSkin2Subgrid(mjCModel* model, mjtNum inflate) {
   char txt[100];
   mjsSkin* skin = mjs_addSkin(&model->spec);
   mju::sprintf_arr(txt, "%sSkin", prefix.c_str());
-  mjs_setString(skin->name, txt);
+  mjs_setName(skin->element, txt);
   mjs_setString(skin->material, skinmaterial.c_str());
   mjuu_copyvec(skin->rgba, skinrgba, 4);
   skin->inflate = inflate;

src/user/user_flexcomp.cc

@@ -108,7 +108,7 @@ bool mjCFlexcomp::Make(mjsBody* body, char* error, int error_sz) {
                  type == mjFCOMPTYPE_GMSH);
 
   // check parent body name
-  if (std::string(mjs_getString(body->name)).empty()) {
+  if (mjs_getName(body->element)->empty()) {
     return comperr(error, "Parent body must have name", error_sz);
   }
 
@@ -410,7 +410,7 @@ bool mjCFlexcomp::Make(mjsBody* body, char* error, int error_sz) {
 
   flex->model = model;
   flex->id = id;
-  mjs_setString(pf->name, name.c_str());
+  mjs_setName(pf->element, name.c_str());
   mjs_setInt(pf->elem, element.data(), element.size());
   mjs_setFloat(pf->texcoord, texcoord.data(), texcoord.size());
   mjs_setInt(pf->elemtexcoord, elemtexcoord.data(), elemtexcoord.size());
@@ -420,7 +420,7 @@ bool mjCFlexcomp::Make(mjsBody* body, char* error, int error_sz) {
 
   // rigid: set parent name, nothing else to do
   if (rigid) {
-    mjs_appendString(pf->vertbody, mjs_getString(body->name));
+    mjs_appendString(pf->vertbody, mjs_getName(body->element)->c_str());
     return true;
   }
 
@@ -443,7 +443,7 @@ bool mjCFlexcomp::Make(mjsBody* body, char* error, int error_sz) {
 
     // pinned or trilinear: parent body
     if (pinned[i] || doftype == mjFCOMPDOF_TRILINEAR) {
-      mjs_appendString(pf->vertbody, mjs_getString(body->name));
+      mjs_appendString(pf->vertbody, mjs_getName(body->element)->c_str());
 
       // add plugin
       if (plugin.active) {
@@ -507,8 +507,8 @@ bool mjCFlexcomp::Make(mjsBody* body, char* error, int error_sz) {
       // construct body name, add to vertbody
       char txt[100];
       mju::sprintf_arr(txt, "%s_%d", name.c_str(), i);
-      mjs_setString(pb->name, txt);
-      mjs_appendString(pf->vertbody, mjs_getString(pb->name));
+      mjs_setName(pb->element, txt);
+      mjs_appendString(pf->vertbody, mjs_getName(pb->element)->c_str());
 
       // clear flex vertex coordinates if allocated
       if (!centered) {
@@ -538,7 +538,7 @@ bool mjCFlexcomp::Make(mjsBody* body, char* error, int error_sz) {
             node[3*(i*4+j*2+k)+0] = i == 0 ? minmax[0] : minmax[3];
             node[3*(i*4+j*2+k)+1] = j == 0 ? minmax[1] : minmax[4];
             node[3*(i*4+j*2+k)+2] = k == 0 ? minmax[2] : minmax[5];
-            mjs_appendString(pf->nodebody, mjs_getString(body->name));
+            mjs_appendString(pf->nodebody, mjs_getName(body->element)->c_str());
             continue;
           }
 
@@ -571,8 +571,8 @@ bool mjCFlexcomp::Make(mjsBody* body, char* error, int error_sz) {
           // construct node name, add to nodebody
           char txt[100];
           mju::sprintf_arr(txt, "%s_%d_%d_%d", name.c_str(), i, j, k);
-          mjs_setString(pb->name, txt);
-          mjs_appendString(pf->nodebody, mjs_getString(pb->name));
+          mjs_setName(pb->element, txt);
+          mjs_appendString(pf->nodebody, mjs_getName(pb->element)->c_str());
         }
       }
     }

src/user/user_mesh.cc

@@ -194,7 +194,6 @@ mjCMesh& mjCMesh::operator=(const mjCMesh& other) {
 
 void mjCMesh::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.file = &spec_file_;
   spec.content_type = &spec_content_type_;
   spec.uservert = &spec_vert_;
@@ -2428,7 +2427,6 @@ mjCSkin& mjCSkin::operator=(const mjCSkin& other) {
 
 void mjCSkin::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.file = &spec_file_;
   spec.material = &spec_material_;
   spec.vert = &spec_vert_;
@@ -3327,7 +3325,6 @@ mjCFlex& mjCFlex::operator=(const mjCFlex& other) {
 
 void mjCFlex::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.material = &spec_material_;
   spec.vertbody = &spec_vertbody_;
   spec.nodebody = &spec_nodebody_;

src/user/user_objects.cc

@@ -747,6 +747,7 @@ void mjCDef::NameSpace(const mjCModel* m) {
 
 void mjCDef::CopyWithoutChildren(const mjCDef& other) {
   name = other.name;
+  elemtype = other.elemtype;
   parent = nullptr;
   child.clear();
   joint_ = other.joint_;
@@ -780,7 +781,6 @@ void mjCDef::PointToLocal() {
   tendon_.PointToLocal();
   actuator_.PointToLocal();
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.joint = &joint_.spec;
   spec.geom = &geom_.spec;
   spec.site = &site_.spec;
@@ -1261,7 +1261,6 @@ void mjCBody::ResetId() {
 
 void mjCBody::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.childclass = &classname;
   spec.userdata = &spec_userdata_;
   spec.plugin.plugin_name = &plugin_name;
@@ -2310,7 +2309,6 @@ bool mjCFrame::IsAncestor(const mjCFrame* child) const {
 
 void mjCFrame::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.childclass = &classname;
   spec.info = &info;
 }
@@ -2461,7 +2459,6 @@ mjtNum* mjCJoint::qvel(const std::string& state_name) {
 
 void mjCJoint::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.userdata = &spec_userdata_;
   spec.info = &info;
   userdata = nullptr;
@@ -2659,7 +2656,6 @@ mjCGeom& mjCGeom::operator=(const mjCGeom& other) {
 // to be called after any default copy constructor
 void mjCGeom::PointToLocal(void) {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.info = &info;
   spec.userdata = &spec_userdata_;
   spec.material = &spec_material_;
@@ -3481,7 +3477,6 @@ mjCSite& mjCSite::operator=(const mjCSite& other) {
 
 void mjCSite::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.info = &info;
   spec.material = &spec_material_;
   spec.userdata = &spec_userdata_;
@@ -3642,7 +3637,6 @@ mjCCamera& mjCCamera::operator=(const mjCCamera& other) {
 
 void mjCCamera::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.userdata = &spec_userdata_;
   spec.targetbody = &spec_targetbody_;
   spec.info = &info;
@@ -3800,7 +3794,6 @@ mjCLight& mjCLight::operator=(const mjCLight& other) {
 
 void mjCLight::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.targetbody = &spec_targetbody_;
   spec.texture = &spec_texture_;
   spec.info = &info;
@@ -3920,7 +3913,6 @@ mjCHField& mjCHField::operator=(const mjCHField& other) {
 
 void mjCHField::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.file = &spec_file_;
   spec.content_type = &spec_content_type_;
   spec.userdata = &spec_userdata_;
@@ -4185,7 +4177,6 @@ mjCTexture& mjCTexture::operator=(const mjCTexture& other) {
 
 void mjCTexture::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.file = &spec_file_;
   spec.data = &data_;
   spec.content_type = &spec_content_type_;
@@ -5054,7 +5045,6 @@ mjCMaterial& mjCMaterial::operator=(const mjCMaterial& other) {
 
 void mjCMaterial::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.textures = &spec_textures_;
   spec.info = &info;
   textures = nullptr;
@@ -5144,7 +5134,6 @@ mjCPair& mjCPair::operator=(const mjCPair& other) {
 
 void mjCPair::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.geomname1 = &spec_geomname1_;
   spec.geomname2 = &spec_geomname2_;
   geomname1 = nullptr;
@@ -5367,7 +5356,6 @@ mjCBodyPair& mjCBodyPair::operator=(const mjCBodyPair& other) {
 
 void mjCBodyPair::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.bodyname1 = &spec_bodyname1_;
   spec.bodyname2 = &spec_bodyname2_;
   spec.info = &info;
@@ -5502,7 +5490,6 @@ mjCEquality& mjCEquality::operator=(const mjCEquality& other) {
 
 void mjCEquality::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.name1 = &spec_name1_;
   spec.name2 = &spec_name2_;
   spec.info = &info;
@@ -5679,7 +5666,6 @@ bool mjCTendon::is_actfrclimited() const {
 
 void mjCTendon::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.material = &spec_material_;
   spec.userdata = &spec_userdata_;
   spec.info = &info;
@@ -6225,7 +6211,6 @@ mjtNum& mjCActuator::ctrl(const std::string& state_name) {
 
 void mjCActuator::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.userdata = &spec_userdata_;
   spec.target = &spec_target_;
   spec.refsite = &spec_refsite_;
@@ -6563,7 +6548,6 @@ mjCSensor& mjCSensor::operator=(const mjCSensor& other) {
 
 void mjCSensor::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.userdata = &spec_userdata_;
   spec.objname = &spec_objname_;
   spec.refname = &spec_refname_;
@@ -7103,7 +7087,6 @@ mjCNumeric& mjCNumeric::operator=(const mjCNumeric& other) {
 
 void mjCNumeric::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.data = &spec_data_;
   spec.info = &info;
   data = nullptr;
@@ -7193,7 +7176,6 @@ mjCText& mjCText::operator=(const mjCText& other) {
 
 void mjCText::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.data = &spec_data_;
   spec.info = &info;
   data = nullptr;
@@ -7274,7 +7256,6 @@ mjCTuple& mjCTuple::operator=(const mjCTuple& other) {
 
 void mjCTuple::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.objtype = (mjIntVec*)&spec_objtype_;
   spec.objname = &spec_objname_;
   spec.objprm = &spec_objprm_;
@@ -7410,7 +7391,6 @@ mjCKey& mjCKey::operator=(const mjCKey& other) {
 
 void mjCKey::PointToLocal() {
   spec.element = static_cast<mjsElement*>(this);
-  spec.name = &name;
   spec.qpos = &spec_qpos_;
   spec.qvel = &spec_qvel_;
   spec.act = &spec_act_;
@@ -7556,7 +7536,6 @@ mjCPlugin::mjCPlugin(mjCModel* _model) {
   mjs_defaultPlugin(&spec);
   elemtype = mjOBJ_PLUGIN;
   spec.plugin_name = &plugin_name;
-  spec.name = &name;
   spec.info = &info;
 
   PointToLocal();

src/user/user_objects.h

@@ -465,7 +465,6 @@ class mjCBody : public mjCBody_, private mjsBody {
   mjsBody spec;
 
   // inherited
-  using mjCBase::name;
   using mjCBase::info;
 
   // used by mjXWriter and mjCModel
@@ -564,7 +563,6 @@ class mjCFrame : public mjCFrame_, private mjsFrame {
   mjCFrame& operator=(const mjCFrame& other);
 
   mjsFrame spec;
-  using mjCBase::name;
   using mjCBase::info;
 
   void CopyFromSpec(void);
@@ -617,7 +615,6 @@ class mjCJoint : public mjCJoint_, private mjsJoint {
   mjCJoint& operator=(const mjCJoint& other);
 
   mjsJoint spec;
-  using mjCBase::name;
   using mjCBase::info;
 
   void CopyFromSpec(void);
@@ -696,7 +693,6 @@ class mjCGeom : public mjCGeom_, private mjsGeom {
   mjCGeom(const mjCGeom& other);
   mjCGeom& operator=(const mjCGeom& other);
 
-  using mjCBase::name;
   mjsGeom spec;                       // variables set by user
   double GetVolume() const;           // compute geom volume
   void SetInertia(void);              // compute and set geom inertia
@@ -769,7 +765,6 @@ class mjCSite : public mjCSite_, private mjsSite {
   mjCBody* GetParent() const { return body; }
 
   // use strings from mjCBase rather than mjStrings from mjsSite
-  using mjCBase::name;
   using mjCBase::info;
 
   // used by mjXWriter and mjCModel
@@ -812,7 +807,6 @@ class mjCCamera : public mjCCamera_, private mjsCamera {
   mjCCamera& operator=(const mjCCamera& other);
 
   mjsCamera spec;
-  using mjCBase::name;
   using mjCBase::info;
 
   // used by mjXWriter and mjCModel
@@ -858,7 +852,6 @@ class mjCLight : public mjCLight_, private mjsLight {
   mjCLight& operator=(const mjCLight& other);
 
   mjsLight spec;
-  using mjCBase::name;
   using mjCBase::info;
 
   // used by mjXWriter and mjCModel
@@ -943,7 +936,6 @@ class mjCFlex: public mjCFlex_, private mjsFlex {
   mjCFlex& operator=(const mjCFlex& other);
 
   mjsFlex spec;
-  using mjCBase::name;
   using mjCBase::info;
 
   void CopyFromSpec(void);
@@ -1049,7 +1041,6 @@ class mjCMesh: public mjCMesh_, private mjsMesh {
   ~mjCMesh();
 
   mjsMesh spec;
-  using mjCBase::name;
   using mjCBase::info;
 
   void CopyFromSpec(void);
@@ -1255,7 +1246,6 @@ class mjCSkin: public mjCSkin_, private mjsSkin {
   ~mjCSkin();
 
   mjsSkin spec;
-  using mjCBase::name;
   using mjCBase::info;
 
   const std::string& File() const { return file_; }
@@ -1313,7 +1303,6 @@ class mjCHField : public mjCHField_, private mjsHField {
   ~mjCHField();
 
   mjsHField spec;
-  using mjCBase::name;
   using mjCBase::info;
 
   void CopyFromSpec(void);
@@ -1365,7 +1354,6 @@ class mjCTexture : public mjCTexture_, private mjsTexture {
   ~mjCTexture();
 
   mjsTexture spec;
-  using mjCBase::name;
   using mjCBase::info;
 
   void CopyFromSpec(void);
@@ -1425,7 +1413,6 @@ class mjCMaterial : public mjCMaterial_, private mjsMaterial {
   mjCMaterial& operator=(const mjCMaterial& other);
 
   mjsMaterial spec;
-  using mjCBase::name;
   using mjCBase::info;
 
   void CopyFromSpec();
@@ -1465,7 +1452,6 @@ class mjCPair : public mjCPair_, private mjsPair {
   mjCPair& operator=(const mjCPair& other);
 
   mjsPair spec;
-  using mjCBase::name;
   using mjCBase::info;
 
   void CopyFromSpec();
@@ -1514,7 +1500,6 @@ class mjCBodyPair : public mjCBodyPair_, private mjsExclude {
   mjCBodyPair& operator=(const mjCBodyPair& other);
 
   mjsExclude spec;
-  using mjCBase::name;
   using mjCBase::info;
 
   void CopyFromSpec();
@@ -1560,7 +1545,6 @@ class mjCEquality : public mjCEquality_, private mjsEquality {
   mjCEquality& operator=(const mjCEquality& other);
 
   mjsEquality spec;
-  using mjCBase::name;
   using mjCBase::info;
 
   void CopyFromSpec();
@@ -1600,7 +1584,6 @@ class mjCTendon : public mjCTendon_, private mjsTendon {
   ~mjCTendon();
 
   mjsTendon spec;
-  using mjCBase::name;
   using mjCBase::info;
 
   void set_material(std::string _material) { material_ = _material; }
@@ -1743,7 +1726,6 @@ class mjCActuator : public mjCActuator_, private mjsActuator {
   mjCActuator& operator=(const mjCActuator& other);
 
   mjsActuator spec;
-  using mjCBase::name;
   using mjCBase::info;
 
   // used by mjXWriter and mjCModel
@@ -1804,7 +1786,6 @@ class mjCSensor : public mjCSensor_, private mjsSensor {
   mjCSensor& operator=(const mjCSensor& other);
 
   mjsSensor spec;
-  using mjCBase::name;
   using mjCBase::info;
 
   // used by mjXWriter and mjCModel
@@ -1846,7 +1827,6 @@ class mjCNumeric : public mjCNumeric_, private mjsNumeric {
   ~mjCNumeric();
 
   mjsNumeric spec;
-  using mjCBase::name;
   using mjCBase::info;
 
   void PointToLocal();
@@ -1878,7 +1858,6 @@ class mjCText : public mjCText_, private mjsText {
   ~mjCText();
 
   mjsText spec;
-  using mjCBase::name;
   using mjCBase::info;
 
   void PointToLocal();
@@ -1915,7 +1894,6 @@ class mjCTuple : public mjCTuple_, private mjsTuple {
   ~mjCTuple();
 
   mjsTuple spec;
-  using mjCBase::name;
   using mjCBase::info;
 
   void PointToLocal();
@@ -1959,7 +1937,6 @@ class mjCKey : public mjCKey_, private mjsKey {
   ~mjCKey();
 
   mjsKey spec;
-  using mjCBase::name;
   using mjCBase::info;
 
   void PointToLocal();

src/xml/xml_native_reader.cc

@@ -1355,7 +1355,7 @@ void mjXReader::OneFlex(XMLElement* elem, mjsFlex* flex) {
 
   // read attributes
   if (ReadAttrTxt(elem, "name", name)) {
-    mjs_setString(flex->name, name.c_str());
+    mjs_setName(flex->element, name.c_str());
   }
   if (ReadAttrTxt(elem, "material", material)) {
     mjs_setString(flex->material, material.c_str());
@@ -1446,7 +1446,7 @@ void mjXReader::OneMesh(XMLElement* elem, mjsMesh* mesh, const mjVFS* vfs) {
 
   // read attributes
   if (ReadAttrTxt(elem, "name", name)) {
-    *mesh->name = name;
+    mjs_setName(mesh->element, name.c_str());
   }
   if (ReadAttrTxt(elem, "content_type", content_type)) {
     *mesh->content_type = content_type;
@@ -1521,7 +1521,7 @@ void mjXReader::OneSkin(XMLElement* elem, mjsSkin* skin, const mjVFS* vfs) {
 
   // read attributes
   if (ReadAttrTxt(elem, "name", name)) {
-    mjs_setString(skin->name, name.c_str());
+    mjs_setName(skin->element, name.c_str());
   }
   auto file = ReadAttrFile(elem, "file", vfs, AssetDir());
   if (file.has_value()) {
@@ -1611,7 +1611,7 @@ void mjXReader::OneMaterial(XMLElement* elem, mjsMaterial* material) {
 
   // read attributes
   if (ReadAttrTxt(elem, "name", name)) {
-    mjs_setString(material->name, name.c_str());
+    mjs_setName(material->element, name.c_str());
   }
 
   bool tex_attributes_found = false;
@@ -1660,7 +1660,7 @@ void mjXReader::OneJoint(XMLElement* elem, mjsJoint* joint) {
 
   // read attributes
   if (ReadAttrTxt(elem, "name", name)) {
-    mjs_setString(joint->name, name.c_str());
+    mjs_setName(joint->element, name.c_str());
   }
   if (MapValue(elem, "type", &n, joint_map, joint_sz)) {
     joint->type = (mjtJoint)n;
@@ -1708,7 +1708,7 @@ void mjXReader::OneGeom(XMLElement* elem, mjsGeom* geom) {
 
   // read attributes
   if (ReadAttrTxt(elem, "name", name)) {
-    mjs_setString(geom->name, name.c_str());
+    mjs_setName(geom->element, name.c_str());
   }
   if (MapValue(elem, "type", &n, geom_map, mjNGEOMTYPES)) {
     geom->type = (mjtGeom)n;
@@ -1780,7 +1780,7 @@ void mjXReader::OneSite(XMLElement* elem, mjsSite* site) {
 
   // read attributes
   if (ReadAttrTxt(elem, "name", name)) {
-    mjs_setString(site->name, name.c_str());
+    mjs_setName(site->element, name.c_str());
   }
   if (MapValue(elem, "type", &n, geom_map, mjNGEOMTYPES)) {
     site->type = (mjtGeom)n;
@@ -1813,7 +1813,7 @@ void mjXReader::OneCamera(XMLElement* elem, mjsCamera* camera) {
 
   // read attributes
   if (ReadAttrTxt(elem, "name", name)) {
-    mjs_setString(camera->name, name.c_str());
+    mjs_setName(camera->element, name.c_str());
   }
   if (ReadAttrTxt(elem, "target", targetbody)) {
     mjs_setString(camera->targetbody, targetbody.c_str());
@@ -1868,7 +1868,7 @@ void mjXReader::OneLight(XMLElement* elem, mjsLight* light) {
 
   // read attributes
   if (ReadAttrTxt(elem, "name", name)) {
-    mjs_setString(light->name, name.c_str());
+    mjs_setName(light->element, name.c_str());
   }
   if (ReadAttrTxt(elem, "texture", texture)) {
     mjs_setString(light->texture, texture.c_str());
@@ -1929,7 +1929,7 @@ void mjXReader::OnePair(XMLElement* elem, mjsPair* pair) {
 
   // read other parameters
   if (ReadAttrTxt(elem, "name", name)) {
-    mjs_setString(pair->name, name.c_str());
+    mjs_setName(pair->element, name.c_str());
   }
   ReadAttrInt(elem, "condim", &pair->condim);
   ReadAttr(elem, "solref", mjNREF, pair->solref, text, false, false);
@@ -1957,7 +1957,7 @@ void mjXReader::OneEquality(XMLElement* elem, mjsEquality* equality) {
   // regular only
   if (!readingdefaults) {
     if (ReadAttrTxt(elem, "name", name)) {
-      mjs_setString(equality->name, name.c_str());
+      mjs_setName(equality->element, name.c_str());
     }
 
     switch (equality->type) {
@@ -2093,7 +2093,7 @@ void mjXReader::OneTendon(XMLElement* elem, mjsTendon* tendon) {
 
   // read attributes
   if (ReadAttrTxt(elem, "name", name)) {
-    mjs_setString(tendon->name, name.c_str());
+    mjs_setName(tendon->element, name.c_str());
   }
   ReadAttrInt(elem, "group", &tendon->group);
   if (ReadAttrTxt(elem, "material", material)) {
@@ -2136,7 +2136,7 @@ void mjXReader::OneActuator(XMLElement* elem, mjsActuator* actuator) {
 
   // common attributes
   if (ReadAttrTxt(elem, "name", name)) {
-    mjs_setString(actuator->name, name.c_str());
+    mjs_setName(actuator->element, name.c_str());
   }
   ReadAttrInt(elem, "group", &actuator->group);
   MapValue(elem, "ctrllimited", &actuator->ctrllimited, TFAuto_map, 3);
@@ -2884,7 +2884,7 @@ void mjXReader::Custom(XMLElement* section) {
 
       // read attributes
       ReadAttrTxt(elem, "name", elname, true);
-      mjs_setString(numeric->name, elname.c_str());
+      mjs_setName(numeric->element, elname.c_str());
       if (ReadAttrInt(elem, "size", &numeric->size)) {
         int sz = numeric->size < 500 ? numeric->size : 500;
         for (int i=0; i < sz; i++) {
@@ -2915,7 +2915,7 @@ void mjXReader::Custom(XMLElement* section) {
 
       // read attributes
       ReadAttrTxt(elem, "name", elname, true);
-      mjs_setString(text->name, elname.c_str());
+      mjs_setName(text->element, elname.c_str());
       ReadAttrTxt(elem, "data", str, true);
       if (str.empty()) {
         throw mjXError(elem, "text field cannot be empty");
@@ -2935,7 +2935,7 @@ void mjXReader::Custom(XMLElement* section) {
 
       // read attributes
       ReadAttrTxt(elem, "name", elname, true);
-      mjs_setString(tuple->name, elname.c_str());
+      mjs_setName(tuple->element, elname.c_str());
 
       // read objects and add
       XMLElement* obj = FirstChildElement(elem);
@@ -3151,7 +3151,7 @@ void mjXReader::Asset(XMLElement* section, const mjVFS* vfs) {
         texture->colorspace = (mjtColorSpace)n;
       }
       if (ReadAttrTxt(elem, "name", texname)) {
-        mjs_setString(texture->name, texname.c_str());
+        mjs_setName(texture->element, texname.c_str());
       }
       if (ReadAttrTxt(elem, "content_type", content_type)) {
         mjs_setString(texture->content_type, content_type.c_str());
@@ -3243,7 +3243,7 @@ void mjXReader::Asset(XMLElement* section, const mjVFS* vfs) {
       // read attributes
       string name, content_type;
       if (ReadAttrTxt(elem, "name", name)) {
-        mjs_setString(hfield->name, name.c_str());
+        mjs_setName(hfield->element, name.c_str());
       }
       if (ReadAttrTxt(elem, "content_type", content_type)) {
         mjs_setString(hfield->content_type, content_type.c_str());
@@ -3406,7 +3406,7 @@ void mjXReader::Body(XMLElement* section, mjsBody* body, mjsFrame* frame,
       // read attributes
       string name;
       if (ReadAttrTxt(elem, "name", name)) {
-        mjs_setString(joint->name, name.c_str());
+        mjs_setName(joint->element, name.c_str());
       }
       ReadAttrInt(elem, "group", &joint->group);
       MapValue(elem, "align", &joint->align, TFAuto_map, 3);
@@ -3478,7 +3478,7 @@ void mjXReader::Body(XMLElement* section, mjsBody* body, mjsFrame* frame,
       // read attributes
       string name, childclass;
       if (ReadAttrTxt(elem, "name", name)) {
-        mjs_setString(pframe->name, name.c_str());
+        mjs_setName(pframe->element, name.c_str());
       }
       if (ReadAttrTxt(elem, "childclass", childclass)) {
         mjs_setString(pframe->childclass, childclass.c_str());
@@ -3579,7 +3579,7 @@ void mjXReader::Body(XMLElement* section, mjsBody* body, mjsFrame* frame,
       // read attributes
       string name, childclass;
       if (ReadAttrTxt(elem, "name", name)) {
-        mjs_setString(child->name, name.c_str());
+        mjs_setName(child->element, name.c_str());
       }
       if (ReadAttrTxt(elem, "childclass", childclass)) {
         mjs_setString(child->childclass, childclass.c_str());
@@ -3688,7 +3688,7 @@ void mjXReader::Contact(XMLElement* section) {
 
       // read name and body names
       if (ReadAttrTxt(elem, "name", exname)) {
-        mjs_setString(exclude->name, exname.c_str());
+        mjs_setName(exclude->element, exname.c_str());
       }
       ReadAttrTxt(elem, "body1", exbody1, true);
       mjs_setString(exclude->bodyname1, exbody1.c_str());
@@ -3870,7 +3870,7 @@ void mjXReader::Sensor(XMLElement* section) {
 
     // read name, noise, userdata
     if (ReadAttrTxt(elem, "name", name)) {
-      mjs_setString(sensor->name, name.c_str());
+      mjs_setName(sensor->element, name.c_str());
     }
     ReadAttr(elem, "cutoff", 1, &sensor->cutoff, text);
     ReadAttr(elem, "noise", 1, &sensor->noise, text);
@@ -4215,7 +4215,7 @@ void mjXReader::Keyframe(XMLElement* section) {
 
     // read name, time
     ReadAttrTxt(elem, "name", name);
-    mjs_setString(key->name, name.c_str());
+    mjs_setName(key->element, name.c_str());
     ReadAttr(elem, "time", 1, &key->time, text);
 
     // read qpos

src/xml/xml_urdf.cc

@@ -216,7 +216,7 @@ void mjXURDF::Parse(
       // if the mass is 0, assume the object is static
       if (!static_body && pbody->mass > 0) {
         mjsJoint* pjoint = mjs_addJoint(pbody, 0);
-        mjs_setString(pjoint->name, (urName[i] + "_free_joint").c_str());
+        mjs_setName(pjoint->element, (urName[i] + "_free_joint").c_str());
         pjoint->type = mjJNT_FREE;
       }
     }
@@ -327,7 +327,7 @@ void mjXURDF::Body(XMLElement* body_elem) {
         mjXUtil::ReadAttrTxt(elem, "name", geom_name);
         name = GetPrefixedName(name);
         if (urGeomNames.find(geom_name) == urGeomNames.end()) {
-          mjs_setString(pgeom->name, geom_name.c_str());
+          mjs_setName(pgeom->element, geom_name.c_str());
           urGeomNames.insert(geom_name);
         } else if (!geom_name.empty()) {
           std::cerr << "WARNING: Geom with duplicate name '" << geom_name
@@ -350,7 +350,7 @@ void mjXURDF::Body(XMLElement* body_elem) {
       mjXUtil::ReadAttrTxt(elem, "name", geom_name);
       geom_name = GetPrefixedName(geom_name);
       if (urGeomNames.find(geom_name) == urGeomNames.end()) {
-        mjs_setString(pgeom->name, geom_name.c_str());
+        mjs_setName(pgeom->element, geom_name.c_str());
         urGeomNames.insert(geom_name);
       } else if (!geom_name.empty()) {
         std::cerr << "WARNING: Geom with duplicate name '" << geom_name
@@ -420,7 +420,7 @@ void mjXURDF::Joint(XMLElement* joint_elem) {
     case 0:   // revolute
     case 1:   // continuous
       pjoint = mjs_addJoint(pbody, 0);
-      mjs_setString(pjoint->name, jntname.c_str());
+      mjs_setName(pjoint->element, jntname.c_str());
       pjoint->type = mjJNT_HINGE;
       mjuu_setvec(pjoint->pos, 0, 0, 0);
       mjuu_copyvec(pjoint->axis, axis, 3);
@@ -428,7 +428,7 @@ void mjXURDF::Joint(XMLElement* joint_elem) {
 
     case 2:   // prismatic
       pjoint = mjs_addJoint(pbody, 0);
-      mjs_setString(pjoint->name, jntname.c_str());
+      mjs_setName(pjoint->element, jntname.c_str());
       pjoint->type = mjJNT_SLIDE;
       mjuu_setvec(pjoint->pos, 0, 0, 0);
       mjuu_copyvec(pjoint->axis, axis, 3);
@@ -439,7 +439,7 @@ void mjXURDF::Joint(XMLElement* joint_elem) {
 
     case 4:   // floating
       pjoint = mjs_addJoint(pbody, 0);
-      mjs_setString(pjoint->name, jntname.c_str());
+      mjs_setName(pjoint->element, jntname.c_str());
       pjoint->type = mjJNT_FREE;
       break;
 
@@ -450,7 +450,7 @@ void mjXURDF::Joint(XMLElement* joint_elem) {
 
       // construct slider along x
       pjoint = mjs_addJoint(pbody, 0);
-      mjs_setString(pjoint->name, (jntname + "_TX").c_str());
+      mjs_setName(pjoint->element, (jntname + "_TX").c_str());
       pjoint->type = mjJNT_SLIDE;
       tmpaxis[0] = mat[0];
       tmpaxis[1] = mat[3];
@@ -460,7 +460,7 @@ void mjXURDF::Joint(XMLElement* joint_elem) {
 
       // construct slider along y
       pjoint1 = mjs_addJoint(pbody, 0);
-      mjs_setString(pjoint1->name, (jntname + "_TY").c_str());
+      mjs_setName(pjoint1->element, (jntname + "_TY").c_str());
       pjoint1->type = mjJNT_SLIDE;
       tmpaxis[0] = mat[1];
       tmpaxis[1] = mat[4];
@@ -470,7 +470,7 @@ void mjXURDF::Joint(XMLElement* joint_elem) {
 
       // construct hinge around z = locaxis
       pjoint2 = mjs_addJoint(pbody, 0);
-      mjs_setString(pjoint2->name, (jntname + "_RZ").c_str());
+      mjs_setName(pjoint2->element, (jntname + "_RZ").c_str());
       pjoint2->type = mjJNT_HINGE;
       mjuu_setvec(pjoint2->pos, 0, 0, 0);
       mjuu_copyvec(pjoint2->axis, axis, 3);
@@ -478,7 +478,7 @@ void mjXURDF::Joint(XMLElement* joint_elem) {
 
     case 6: // ball joint
       pjoint = mjs_addJoint(pbody, 0);
-      mjs_setString(pjoint->name, jntname.c_str());
+      mjs_setName(pjoint->element, jntname.c_str());
       pjoint->type = mjJNT_BALL;
       mjuu_setvec(pjoint->pos, 0, 0, 0);
       mjuu_copyvec(pjoint->axis, axis, 3);
@@ -530,7 +530,7 @@ mjsGeom* mjXURDF::Geom(XMLElement* geom_elem, mjsBody* pbody, bool collision) {
 
   // add BOX geom, modify type later
   mjsGeom* pgeom = mjs_addGeom(pbody, 0);
-  mjs_setString(pgeom->name, "");
+  mjs_setName(pgeom->element, "");
   pgeom->type = mjGEOM_BOX;
   if (collision) {
     pgeom->contype = 1;
@@ -624,7 +624,7 @@ mjsGeom* mjXURDF::Geom(XMLElement* geom_elem, mjsBody* pbody, bool collision) {
     // set fields
     if (newmesh) {
       mjs_setString(pmesh->file, meshfile.c_str());
-      mjs_setString(pmesh->name, meshname.c_str());
+      mjs_setName(pmesh->element, meshname.c_str());
       pmesh->scale[0] = meshscale[0];
       pmesh->scale[1] = meshscale[1];
       pmesh->scale[2] = meshscale[2];
@@ -726,7 +726,7 @@ void mjXURDF::AddToTree(int n) {
   // add this body
   if (urName[n] != "world") {
     child = mjs_addBody(parent, 0);
-    mjs_setString(child->name, urName[n].c_str());
+    mjs_setName(child->element, urName[n].c_str());
   }
 
   // add children recursively

test/user/user_api_test.cc

@@ -54,11 +54,11 @@ TEST_F(MujocoTest, GetSetData) {
     double vec[10] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
     const char* str = "sitename";
 
-    mjs_setString(site->name, str);
+    mjs_setName(site->element, str);
     mjs_setDouble(site->userdata, vec, 10);
   }
 
-  EXPECT_THAT(mjs_getString(site->name), HasSubstr("sitename"));
+  EXPECT_THAT(mjs_getName(site->element)->c_str(), HasSubstr("sitename"));
 
   int nsize;
   const double* vec = mjs_getDouble(site->userdata, &nsize);
@@ -199,7 +199,7 @@ TEST_F(PluginTest, DeletePlugin) {
   mjsBody* body = mjs_addBody(mjs_findBody(spec, "world"), 0);
   mjsJoint* joint = mjs_addJoint(body, 0);
   mjsGeom* geom = mjs_addGeom(body, 0);
-  mjs_setString(joint->name, "j1");
+  mjs_setName(joint->element, "j1");
   joint->type = mjJNT_SLIDE;
   geom->size[0] = 1;
 
@@ -358,10 +358,10 @@ TEST_F(PluginTest, AttachExplicitPlugin) {
   mjs_activatePlugin(child, "mujoco.sensor.touch_grid");
   mjs_setString(plugin->plugin_name, "mujoco.sensor.touch_grid");
   mjs_setString(sensor->plugin.plugin_name, "mujoco.sensor.touch_grid");
-  mjs_setString(body->name, "body");
-  mjs_setString(sensor->name, "touch2");
+  mjs_setName(body->element, "body");
+  mjs_setName(sensor->element, "touch2");
   mjs_setString(sensor->objname, "touch2");
-  mjs_setString(site->name, "touch2");
+  mjs_setName(site->element, "touch2");
   geom->size[0] = 0.1;
   site->size[0] = 0.001;
   sensor->type = mjSENS_PLUGIN;
@@ -470,8 +470,8 @@ TEST_F(MujocoTest, RecompileFails) {
 
   mjsMaterial* mat1 = mjs_addMaterial(spec, 0);
   mjsMaterial* mat2 = mjs_addMaterial(spec, 0);
-  mjs_setString(mat1->name, "yellow");
-  mjs_setString(mat2->name, "yellow");
+  mjs_setName(mat1->element, "yellow");
+  mjs_setName(mat2->element, "yellow");
 
   EXPECT_EQ(mj_recompile(spec, 0, model, data), -1);
   EXPECT_STREQ(mjs_getError(spec), "Error: repeated name 'yellow' in material");
@@ -752,7 +752,7 @@ TEST_F(PluginTest, TextureFromBuffer) {
   mjSpec* spec = mj_makeSpec();
 
   mjsTexture* t1 = mjs_addTexture(spec);
-  mjs_setString(t1->name, "tex1");
+  mjs_setName(t1->element, "tex1");
   t1->type = mjTEXTURE_2D;
   t1->width = 3;
   t1->height = 2;
@@ -760,7 +760,7 @@ TEST_F(PluginTest, TextureFromBuffer) {
   mjs_setBuffer(t1->data, (std::byte*)tex1, 18);
 
   mjsTexture* t2 = mjs_addTexture(spec);
-  mjs_setString(t2->name, "tex2");
+  mjs_setName(t2->element, "tex2");
   t2->type = mjTEXTURE_2D;
   t2->width = 3;
   t2->height = 2;
@@ -768,7 +768,7 @@ TEST_F(PluginTest, TextureFromBuffer) {
   mjs_setBuffer(t2->data, (std::byte*)tex2, 18);
 
   mjsMaterial* mat = mjs_addMaterial(spec, nullptr);
-  mjs_setString(mat->name, "mat");
+  mjs_setName(mat->element, "mat");
   mjs_setInStringVec(mat->textures, mjTEXROLE_RGB, "tex1");
   mjs_setInStringVec(mat->textures, mjTEXROLE_ORM, "tex2");
 
@@ -1706,7 +1706,7 @@ TEST_F(MujocoTest, AttachSpecToSite) {
   EXPECT_THAT(world, NotNull());
   mjsFrame* frame = mjs_addFrame(world, 0);
   EXPECT_THAT(frame, NotNull());
-  mjs_setString(frame->name, "world");
+  mjs_setName(frame->element, "world");
   mjs_setFrame(mjs_firstChild(world, mjOBJ_BODY, 0), frame);
   mjs_setFrame(mjs_firstChild(world, mjOBJ_CAMERA, 0), frame);
 
@@ -1784,7 +1784,7 @@ TEST_F(MujocoTest, AttachSpecToBody) {
   EXPECT_THAT(world, NotNull());
   mjsFrame* frame = mjs_addFrame(world, 0);
   EXPECT_THAT(frame, NotNull());
-  mjs_setString(frame->name, "world");
+  mjs_setName(frame->element, "world");
   mjs_setFrame(mjs_firstChild(world, mjOBJ_BODY, 0), frame);
   mjs_setFrame(mjs_firstChild(world, mjOBJ_CAMERA, 0), frame);
 
@@ -2152,14 +2152,14 @@ TEST_F(MujocoTest, InitTexture) {
   EXPECT_THAT(spec, NotNull());
 
   mjsTexture* texture = mjs_addTexture(spec);
-  mjs_setString(texture->name, "checker");
+  mjs_setName(texture->element, "checker");
   texture->type = mjTEXTURE_CUBE;
   texture->builtin = mjBUILTIN_CHECKER;
   texture->width = 300;
   texture->height = 300;
 
   mjsMaterial* material = mjs_addMaterial(spec, 0);
-  mjs_setString(material->name, "floor");
+  mjs_setName(material->element, "floor");
   mjs_setInStringVec(material->textures, mjTEXROLE_RGB, "checker");
 
   mjsGeom* floor = mjs_addGeom(mjs_findBody(spec, "world"), 0);
@@ -2848,8 +2848,8 @@ TEST_F(MujocoTest, SetFrameReverseOrder) {
   mjsBody* world = mjs_findBody(spec, "world");
   mjsFrame* child = mjs_addFrame(world, nullptr);
   mjsFrame* parent = mjs_addFrame(world, nullptr);
-  mjs_setString(child->name, "child");
-  mjs_setString(parent->name, "parent");
+  mjs_setName(child->element, "child");
+  mjs_setName(parent->element, "parent");
   mjs_setFrame(child->element, parent);
   mjSpec* copy = mj_copySpec(spec);
   EXPECT_THAT(copy, NotNull());

test/user/user_model_test.cc

@@ -709,7 +709,7 @@ TEST_F(MujocoTest, Modeldir) {
   mjsGeom* geom = mjs_addGeom(mjs_findBody(child, "world"), 0);
   mjs_setString(child->meshdir, "meshdir");
   mjs_setString(mesh->file, "cube.obj");
-  mjs_setString(mesh->name, "cube");
+  mjs_setName(mesh->element, "cube");
   mjs_setString(geom->meshname, "cube");
   mjs_setFrame(geom->element, frame);
   geom->type = mjGEOM_MESH;

test/xml/xml_urdf_test.cc

@@ -308,9 +308,9 @@ TEST_F(MujocoTest, RepeatedMeshName) {
   EXPECT_THAT(mesh1, NotNull());
   EXPECT_THAT(mesh2, NotNull());
   EXPECT_THAT(mesh3, IsNull());
-  EXPECT_STREQ(mjs_getString(mesh->name), "mesh");
-  EXPECT_STREQ(mjs_getString(mesh1->name), "mesh1");
-  EXPECT_STREQ(mjs_getString(mesh2->name), "mesh2");
+  EXPECT_STREQ(mjs_getName(mesh->element)->c_str(), "mesh");
+  EXPECT_STREQ(mjs_getName(mesh1->element)->c_str(), "mesh1");
+  EXPECT_STREQ(mjs_getName(mesh2->element)->c_str(), "mesh2");
 
   mj_deleteSpec(spec);
 }