[Feature] Allow register multi-name for a module simultaneously (#775)

* allow register multi-name for a module simultaneously

* add assertion for name type

* use isintance intead of is_str

* fix bug in unit test

* fix unit test

mmcv/utils/registry.py

@@ -2,7 +2,7 @@ import inspect
 import warnings
 from functools import partial
 
-from .misc import is_str
+from .misc import is_seq_of
 
 
 class Registry:
@@ -54,10 +54,18 @@ class Registry:
 
         if module_name is None:
             module_name = module_class.__name__
-        if not force and module_name in self._module_dict:
-            raise KeyError(f'{module_name} is already registered '
+        if isinstance(module_name, str):
+            module_name = [module_name]
+        else:
+            assert is_seq_of(
+                module_name,
+                str), ('module_name should be either of None, an '
+                       f'instance of str or list, but got {type(module_name)}')
+        for name in module_name:
+            if not force and name in self._module_dict:
+                raise KeyError(f'{name} is already registered '
                                f'in {self.name}')
-        self._module_dict[module_name] = module_class
+            self._module_dict[name] = module_class
 
     def deprecated_register_module(self, cls=None, force=False):
         warnings.warn(
@@ -157,7 +165,7 @@ def build_from_cfg(cfg, registry, default_args=None):
             args.setdefault(name, value)
 
     obj_type = args.pop('type')
-    if is_str(obj_type):
+    if isinstance(obj_type, str):
         obj_cls = registry.get(obj_type)
         if obj_cls is None:
             raise KeyError(

tests/test_utils/test_registry.py

@@ -58,6 +58,9 @@ def test_registry():
     CATS.register_module(name='Sphynx', module=SphynxCat)
     assert CATS.get('Sphynx') is SphynxCat
 
+    CATS.register_module(name=['Sphynx1', 'Sphynx2'], module=SphynxCat)
+    assert CATS.get('Sphynx2') is SphynxCat
+
     repr_str = 'Registry(name=cat, items={'
     repr_str += ("'BritishShorthair': <class 'test_registry.test_registry."
                  "<locals>.BritishShorthair'>, ")
@@ -66,10 +69,18 @@ def test_registry():
     repr_str += ("'Siamese': <class 'test_registry.test_registry."
                  "<locals>.SiameseCat'>, ")
     repr_str += ("'Sphynx': <class 'test_registry.test_registry."
+                 "<locals>.SphynxCat'>, ")
+    repr_str += ("'Sphynx1': <class 'test_registry.test_registry."
+                 "<locals>.SphynxCat'>, ")
+    repr_str += ("'Sphynx2': <class 'test_registry.test_registry."
                  "<locals>.SphynxCat'>")
     repr_str += '})'
     assert repr(CATS) == repr_str
 
+    # name type
+    with pytest.raises(AssertionError):
+        CATS.register_module(name=7474741, module=SphynxCat)
+
     # the registered module should be a class
     with pytest.raises(TypeError):
         CATS.register_module(0)