add mjs_detachDefault to delete a default class from mjSpec

PiperOrigin-RevId: 738452369
Change-Id: I5a53a6dc8f89e1e8136aeefc09d7d9b7b7204e1f

python/mujoco/introspect/enums.py

@@ -287,6 +287,7 @@ ENUMS: Mapping[str, EnumDecl] = dict([
              ('mjOBJ_PLUGIN', 25),
              ('mjNOBJECT', 26),
              ('mjOBJ_FRAME', 100),
+             ('mjOBJ_DEFAULT', 101),
          ]),
      )),
     ('mjtConstraint',

python/mujoco/introspect/functions.py

@@ -9154,7 +9154,27 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
                  ),
              ),
          ),
-         doc='Detach body from mjSpec, remove all references and delete the body, return 0 on success.',  # pylint: disable=line-too-long
+         doc='Delete body and descendants from mjSpec, remove all references, return 0 on success.',  # pylint: disable=line-too-long
+     )),
+    ('mjs_detachDefault',
+     FunctionDecl(
+         name='mjs_detachDefault',
+         return_type=ValueType(name='int'),
+         parameters=(
+             FunctionParameterDecl(
+                 name='s',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjSpec'),
+                 ),
+             ),
+             FunctionParameterDecl(
+                 name='d',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsDefault'),
+                 ),
+             ),
+         ),
+         doc='Delete default class and descendants from mjSpec, remove all references, return 0 on success.',  # pylint: disable=line-too-long
      )),
     ('mjs_addBody',
      FunctionDecl(
@@ -9954,7 +9974,7 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
      FunctionDecl(
          name='mjs_findDefault',
          return_type=PointerType(
-             inner_type=ValueType(name='mjsDefault', is_const=True),
+             inner_type=ValueType(name='mjsDefault'),
          ),
          parameters=(
              FunctionParameterDecl(

python/mujoco/specs.cc

@@ -448,7 +448,7 @@ PYBIND11_MODULE(_specs, m) {
       py::return_value_policy::reference_internal);
   mjSpec.def(
       "find_default",
-      [](MjSpec& self, std::string& classname) -> const raw::MjsDefault* {
+      [](MjSpec& self, std::string& classname) -> raw::MjsDefault* {
         return mjs_findDefault(self.ptr, classname.c_str());
       },
       py::return_value_policy::reference_internal);
@@ -499,6 +499,11 @@ PYBIND11_MODULE(_specs, m) {
         return mjs_addDefault(spec->ptr, classname.c_str(), parent);
       },
       py::return_value_policy::reference_internal);
+  mjSpec.def("detach_default", [](MjSpec& self, raw::MjsDefault& def) {
+    if (mjs_detachDefault(self.ptr, &def) != 0) {
+      throw pybind11::value_error(mjs_getError(self.ptr));
+    }
+  });
   mjSpec.def_property_readonly(
       "default",
       [](MjSpec& self) -> raw::MjsDefault* {

python/mujoco/specs_test.py

@@ -589,6 +589,12 @@ class SpecsTest(absltest.TestCase):
     spec.compile()
     self.assertEqual(spec.to_xml(), XML)
 
+    # test delete default
+    def1 = spec.find_default('def1')
+    spec.detach_default(def1)
+    def1 = spec.find_default('def1')
+    self.assertIsNone(def1)
+
   def test_element_list(self):
     spec = mujoco.MjSpec()
     sensor1 = spec.add_sensor()