Change set_default and default to classname in the bindings.

Having defaults in the names of the attribute or function names is confusing for the users since the defaults are not re-applied but are only used for writing to XML. The alternative would be to change mjs_setDefault to re-apply them, but this would overwrite any other attribute set by the user so far.

PiperOrigin-RevId: 726431090
Change-Id: I41f4a23e1722e278b0ecc0a00b07db9b384fe994

python/mujoco/specs.cc

@@ -595,16 +595,14 @@ PYBIND11_MODULE(_specs, m) {
               [](raw::MjsBody& self, raw::MjsFrame& frame) -> void {
                 mjs_setFrame(self.element, &frame);
               });
-  mjsBody.def("set_default",
+  mjsBody.def_property(
-              [](raw::MjsBody& self, raw::MjsDefault& default_) -> void {
+      "classname",
-                mjs_setDefault(self.element, &default_);
-              });
-  mjsBody.def(
-      "default",
       [](raw::MjsBody& self) -> raw::MjsDefault* {
         return mjs_getDefault(self.element);
       },
-      py::return_value_policy::reference_internal);
+      [](raw::MjsBody& self, raw::MjsDefault& default_) -> void {
+        mjs_setDefault(self.element, &default_);
+      });
   mjsBody.def(
       "find_all",
       [](raw::MjsBody& self, mjtObj objtype) -> py::list {
@@ -837,63 +835,60 @@ PYBIND11_MODULE(_specs, m) {
   mjsGeom.def("set_frame", [](raw::MjsGeom& self, raw::MjsFrame& frame) {
     mjs_setFrame(self.element, &frame);
   });
-  mjsGeom.def("set_default", [](raw::MjsGeom& self, raw::MjsDefault& def) {
-    mjs_setDefault(self.element, &def);
-  });
   mjsGeom.def_property_readonly(
       "parent",
       [](raw::MjsGeom& self) -> raw::MjsBody* {
         return mjs_getParent(self.element);
       },
       py::return_value_policy::reference_internal);
-  mjsGeom.def(
+  mjsGeom.def_property(
-      "default",
+      "classname",
       [](raw::MjsGeom& self) -> raw::MjsDefault* {
         return mjs_getDefault(self.element);
       },
-      py::return_value_policy::reference_internal);
+      [](raw::MjsGeom& self, raw::MjsDefault& default_) -> void {
+        mjs_setDefault(self.element, &default_);
+      });
 
   // ============================= MJSJOINT ====================================
   mjsJoint.def("delete", [](raw::MjsJoint& self) { mjs_delete(self.element); });
   mjsJoint.def("set_frame", [](raw::MjsJoint& self, raw::MjsFrame& frame) {
     mjs_setFrame(self.element, &frame);
   });
-  mjsJoint.def("set_default", [](raw::MjsJoint& self, raw::MjsDefault& def) {
-    mjs_setDefault(self.element, &def);
-  });
   mjsJoint.def_property_readonly(
       "parent",
       [](raw::MjsJoint& self) -> raw::MjsBody* {
         return mjs_getParent(self.element);
       },
       py::return_value_policy::reference_internal);
-  mjsJoint.def(
+  mjsJoint.def_property(
-      "default",
+      "classname",
       [](raw::MjsJoint& self) -> raw::MjsDefault* {
         return mjs_getDefault(self.element);
       },
-      py::return_value_policy::reference_internal);
+      [](raw::MjsJoint& self, raw::MjsDefault& default_) -> void {
+        mjs_setDefault(self.element, &default_);
+      });
 
   // ============================= MJSSITE =====================================
   mjsSite.def("delete", [](raw::MjsSite& self) { mjs_delete(self.element); });
   mjsSite.def("set_frame", [](raw::MjsSite& self, raw::MjsFrame& frame) {
     mjs_setFrame(self.element, &frame);
   });
-  mjsSite.def("set_default", [](raw::MjsSite& self, raw::MjsDefault& def) {
-    mjs_setDefault(self.element, &def);
-  });
   mjsSite.def_property_readonly(
       "parent",
       [](raw::MjsSite& self) -> raw::MjsBody* {
         return mjs_getParent(self.element);
       },
       py::return_value_policy::reference_internal);
-  mjsSite.def(
+  mjsSite.def_property(
-      "default",
+      "classname",
       [](raw::MjsSite& self) -> raw::MjsDefault* {
         return mjs_getDefault(self.element);
       },
-      py::return_value_policy::reference_internal);
+      [](raw::MjsSite& self, raw::MjsDefault& default_) -> void {
+        mjs_setDefault(self.element, &default_);
+      });
   mjsSite.def(
       "attach_body",
       [](raw::MjsSite& self, raw::MjsBody& body,
@@ -918,115 +913,102 @@ PYBIND11_MODULE(_specs, m) {
   mjsCamera.def("set_frame", [](raw::MjsCamera& self, raw::MjsFrame& frame) {
     mjs_setFrame(self.element, &frame);
   });
-  mjsCamera.def("set_default", [](raw::MjsCamera& self, raw::MjsDefault& def) {
-    mjs_setDefault(self.element, &def);
-  });
   mjsCamera.def_property_readonly(
       "parent",
       [](raw::MjsCamera& self) -> raw::MjsBody* {
         return mjs_getParent(self.element);
       },
       py::return_value_policy::reference_internal);
-  mjsCamera.def(
+  mjsCamera.def_property(
-      "default",
+      "classname",
       [](raw::MjsCamera& self) -> raw::MjsDefault* {
         return mjs_getDefault(self.element);
       },
-      py::return_value_policy::reference_internal);
+      [](raw::MjsCamera& self, raw::MjsDefault& default_) -> void {
+        mjs_setDefault(self.element, &default_);
+      });
 
   // ============================= MJSLIGHT ====================================
   mjsLight.def("delete", [](raw::MjsLight& self) { mjs_delete(self.element); });
   mjsLight.def("set_frame", [](raw::MjsLight& self, raw::MjsFrame& frame) {
     mjs_setFrame(self.element, &frame);
   });
-  mjsLight.def("set_default", [](raw::MjsLight& self, raw::MjsDefault& def) {
-    mjs_setDefault(self.element, &def);
-  });
   mjsLight.def_property_readonly(
       "parent",
       [](raw::MjsLight& self) -> raw::MjsBody* {
         return mjs_getParent(self.element);
       },
       py::return_value_policy::reference_internal);
-  mjsLight.def(
+  mjsLight.def_property(
-      "default",
+      "classname",
       [](raw::MjsLight& self) -> raw::MjsDefault* {
         return mjs_getDefault(self.element);
       },
-      py::return_value_policy::reference_internal);
+      [](raw::MjsLight& self, raw::MjsDefault& default_) -> void {
+        mjs_setDefault(self.element, &default_);
+      });
 
   // ============================= MJSMATERIAL =================================
   mjsMaterial.def("delete",
                   [](raw::MjsMaterial& self) { mjs_delete(self.element); });
-  mjsMaterial.def("set_default",
+  mjsMaterial.def_property(
-                  [](raw::MjsMaterial& self, raw::MjsDefault& def) {
+      "classname",
-                    mjs_setDefault(self.element, &def);
-                  });
-  mjsMaterial.def(
-      "default",
       [](raw::MjsMaterial& self) -> raw::MjsDefault* {
         return mjs_getDefault(self.element);
       },
-      py::return_value_policy::reference_internal);
+      [](raw::MjsMaterial& self, raw::MjsDefault& default_) -> void {
+        mjs_setDefault(self.element, &default_);
+      });
 
   // ============================= MJSMESH =====================================
   mjsMesh.def("delete", [](raw::MjsMesh& self) { mjs_delete(self.element); });
-  mjsMesh.def("set_default", [](raw::MjsMesh& self, raw::MjsDefault& def) {
+  mjsMesh.def_property(
-    mjs_setDefault(self.element, &def);
+      "classname",
-  });
-  mjsMesh.def(
-      "default",
       [](raw::MjsMesh& self) -> raw::MjsDefault* {
         return mjs_getDefault(self.element);
       },
-      py::return_value_policy::reference_internal);
+      [](raw::MjsMesh& self, raw::MjsDefault& default_) -> void {
+        mjs_setDefault(self.element, &default_);
+      });
 
   // ============================= MJSPAIR =====================================
   mjsPair.def("delete", [](raw::MjsPair& self) { mjs_delete(self.element); });
-  mjsPair.def("set_default", [](raw::MjsPair& self, raw::MjsDefault& def) {
+  mjsPair.def_property(
-    mjs_setDefault(self.element, &def);
+      "classname",
-  });
-  mjsPair.def(
-      "default",
       [](raw::MjsPair& self) -> raw::MjsDefault* {
         return mjs_getDefault(self.element);
       },
-      py::return_value_policy::reference_internal);
+      [](raw::MjsPair& self, raw::MjsDefault& default_) -> void {
+        mjs_setDefault(self.element, &default_);
+      });
 
   // ============================= MJSEQUAL ====================================
   mjsEquality.def("delete",
                   [](raw::MjsEquality& self) { mjs_delete(self.element); });
-  mjsEquality.def("set_default",
+  mjsEquality.def_property(
-                  [](raw::MjsEquality& self, raw::MjsDefault& def) {
+      "classname",
-                    mjs_setDefault(self.element, &def);
-                  });
-  mjsEquality.def(
-      "default",
       [](raw::MjsEquality& self) -> raw::MjsDefault* {
         return mjs_getDefault(self.element);
       },
-      py::return_value_policy::reference_internal);
+      [](raw::MjsEquality& self, raw::MjsDefault& default_) -> void {
+        mjs_setDefault(self.element, &default_);
+      });
 
   // ============================= MJSACTUATOR =================================
   mjsActuator.def("delete",
                   [](raw::MjsActuator& self) { mjs_delete(self.element); });
-  mjsActuator.def("set_default",
+  mjsActuator.def_property(
-                  [](raw::MjsActuator& self, raw::MjsDefault& def) {
+      "classname",
-                    mjs_setDefault(self.element, &def);
-                  });
-  mjsActuator.def(
-      "default",
       [](raw::MjsActuator& self) -> raw::MjsDefault* {
         return mjs_getDefault(self.element);
       },
-      py::return_value_policy::reference_internal);
+      [](raw::MjsActuator& self, raw::MjsDefault& default_) -> void {
+        mjs_setDefault(self.element, &default_);
+      });
 
   // ============================= MJSTENDON ===================================
   mjsTendon.def("delete",
                 [](raw::MjsTendon& self) { mjs_delete(self.element); });
-  mjsTendon.def("set_default", [](raw::MjsTendon& self, raw::MjsDefault& def) {
-    mjs_setDefault(self.element, &def);
-  });
   mjsTendon.def(
       "default",
       [](raw::MjsTendon& self) -> raw::MjsDefault* {

python/mujoco/specs_test.py

@@ -528,22 +528,7 @@ class SpecsTest(absltest.TestCase):
       spec.to_xml()
 
   def test_modelname_default_class(self):
-    spec = mujoco.MjSpec()
+    XML = textwrap.dedent("""\
-    spec.modelname = 'test'
-
-    main = spec.default()
-    main.geom.size[0] = 2
-
-    def1 = spec.add_default('def1', main)
-    def1.geom.size[0] = 3
-
-    spec.worldbody.add_geom(def1)
-    spec.worldbody.add_geom(main)
-
-    spec.compile()
-    self.assertEqual(
-        spec.to_xml(),
-        textwrap.dedent("""\
         <mujoco model="test">
           <compiler angle="radian"/>
 
@@ -559,8 +544,8 @@ class SpecsTest(absltest.TestCase):
             <geom/>
           </worldbody>
         </mujoco>
-    """),
+    """)
-    )
+
     spec = mujoco.MjSpec()
     spec.modelname = 'test'
 
@@ -574,26 +559,38 @@ class SpecsTest(absltest.TestCase):
     spec.worldbody.add_geom(main)
 
     spec.compile()
-    self.assertEqual(
+    self.assertEqual(spec.to_xml(), XML)
-        spec.to_xml(),
+    spec = mujoco.MjSpec()
-        textwrap.dedent("""\
+    spec.modelname = 'test'
-        <mujoco model="test">
-          <compiler angle="radian"/>
 
-          <default>
+    main = spec.default()
-            <geom size="2 0 0"/>
+    main.geom.size[0] = 2
-            <default class="def1">
+    def1 = spec.add_default('def1', main)
-              <geom size="3 0 0"/>
+    def1.geom.size[0] = 3
-            </default>
-          </default>
 
-          <worldbody>
+    geom1 = spec.worldbody.add_geom(def1)
-            <geom class="def1"/>
+    geom2 = spec.worldbody.add_geom()
-            <geom/>
+    self.assertEqual(geom1.classname.name, 'def1')
-          </worldbody>
+    self.assertEqual(geom2.classname.name, 'main')
-        </mujoco>
+
-    """),
+    spec.compile()
-    )
+    self.assertEqual(spec.to_xml(), XML)
+
+    spec = mujoco.MjSpec()
+    spec.modelname = 'test'
+
+    main = spec.default()
+    main.geom.size[0] = 2
+    def1 = spec.add_default('def1', main)
+    def1.geom.size[0] = 3
+
+    geom1 = spec.worldbody.add_geom(size=[3, 0, 0])
+    geom2 = spec.worldbody.add_geom(size=[2, 0, 0])
+    geom1.classname = def1
+    geom2.classname = main  # actually redundant, since main is always applied
+
+    spec.compile()
+    self.assertEqual(spec.to_xml(), XML)
 
   def test_element_list(self):
     spec = mujoco.MjSpec()