Deprecate get_resolver() and add new has_resolver()

Fixes omry#608

news/608.api_change

@@ -0,0 +1 @@
+`OmegaConf.get_resolver()` is deprecated: use the new `OmegaConf.has_resolver()` to check for the existence of a resolver.

news/608.feature

@@ -0,0 +1 @@
+New function `OmegaConf.has_resolver()` allows checking whether a resolver has already been registered.

omegaconf/base.py

@@ -593,7 +593,7 @@ def _evaluate_custom_resolver(
     ) -> Any:
         from omegaconf import OmegaConf
 
-        resolver = OmegaConf.get_resolver(inter_type)
+        resolver = OmegaConf._get_resolver(inter_type)
         if resolver is not None:
             root_node = self._get_root()
             return resolver(root_node, self, inter_args, inter_args_str)

omegaconf/omegaconf.py

@@ -529,8 +529,28 @@ def resolver_wrapper(
         # noinspection PyProtectedMember
         BaseContainer._resolvers[name] = resolver_wrapper
 
-    @staticmethod
+    @classmethod
+    def has_resolver(cls, name: str) -> bool:
+        return cls._get_resolver(name) is not None
+
+    # DEPRECATED: remove in 2.2
+    @classmethod
     def get_resolver(
+        cls,
+        name: str,
+    ) -> Optional[
+        Callable[[Container, Container, Tuple[Any, ...], Tuple[str, ...]], Any]
+    ]:
+        warnings.warn(
+            "`OmegaConf.get_resolver()` is deprecated (see https://github.com/omry/omegaconf/issues/608)",
+            UserWarning,
+            stacklevel=2,
+        )
+
+        return cls._get_resolver(name)
+
+    @staticmethod
+    def _get_resolver(
         name: str,
     ) -> Optional[
         Callable[[Container, Container, Tuple[Any, ...], Tuple[str, ...]], Any]

tests/test_interpolation.py

@@ -363,20 +363,20 @@ def foo() -> int:
         OmegaConf.register_new_resolver("foo", lambda: 10)
 
 
-def test_clear_resolvers(restore_resolvers: Any) -> None:
-    assert OmegaConf.get_resolver("foo") is None
+def test_clear_resolvers_and_has_resolver(restore_resolvers: Any) -> None:
+    assert not OmegaConf.has_resolver("foo")
     OmegaConf.register_new_resolver("foo", lambda x: x + 10)
-    assert OmegaConf.get_resolver("foo") is not None
+    assert OmegaConf.has_resolver("foo")
     OmegaConf.clear_resolvers()
-    assert OmegaConf.get_resolver("foo") is None
+    assert not OmegaConf.has_resolver("foo")
 
 
-def test_clear_resolvers_legacy(restore_resolvers: Any) -> None:
-    assert OmegaConf.get_resolver("foo") is None
+def test_clear_resolvers_and_has_resolver_legacy(restore_resolvers: Any) -> None:
+    assert not OmegaConf.has_resolver("foo")
     OmegaConf.legacy_register_resolver("foo", lambda x: int(x) + 10)
-    assert OmegaConf.get_resolver("foo") is not None
+    assert OmegaConf.has_resolver("foo")
     OmegaConf.clear_resolvers()
-    assert OmegaConf.get_resolver("foo") is None
+    assert not OmegaConf.has_resolver("foo")
 
 
 def test_register_resolver_1(restore_resolvers: Any) -> None: