Added clear_resolver method to OmegaConf (#770)

CONTRIBUTING.md

@@ -18,8 +18,8 @@ pre-commit will verify your code lints cleanly when you commit. You can use `git
 OmegaConf is compatible with Python 3.6.4 and newer. Unfortunately Mac comes with older versions.
 
 One way to install multiple Python versions on Mac to to use pyenv.
-The instructions [here](https://github.com/GoogleCloudPlatform/python-docs-samples/blob/master/MAC_SETUP.md) 
-will provide full details. It shows how to use pyenv on mac to install multiple versions of Python and have 
+The instructions [here](https://github.com/GoogleCloudPlatform/python-docs-samples/blob/master/MAC_SETUP.md)
+will provide full details. It shows how to use pyenv on mac to install multiple versions of Python and have
 pyenv make specific versions available in specific directories automatically.
 This plays well with Conda, which supports a single Python version. Pyenv will provide the versions not installed by Conda (which are used when running nox).
 
@@ -49,23 +49,24 @@ Sessions defined in /home/omry/dev/omegaconf/noxfile.py:
 * test_jupyter_notebook-3.8
 * test_jupyter_notebook-3.9
 ```
+
 To run a specific session use `-s`, for example `nox -s lint` will run linting
 
 
 OmegaConf is formatted with black, to format your code automatically use `black .`
 
-Imports are sorted using isort, use `isort .` to sort all imports prior to pushing.  
+Imports are sorted using isort, use `isort .` to sort all imports prior to pushing.
 
 To build the docs execute `nox -s docs` or `make`(inside docs folder). Make gives you different options, for example, you can build the docs as html files with `make html`. Once the docs are built you can open `index.html` in the build directory to view the generated docs with your browser.
 
 ### Modifying Jupyter notebook
 
 In order to change the Jupyter notebook you first need to open it with `jupyter notebook`.
-Change the cell you want and then, execute it so the expected output is shown. 
-Note that the output after you execute the cell is saved as expected ouput for further 
+Change the cell you want and then, execute it so the expected output is shown.
+Note that the output after you execute the cell is saved as expected ouput for further
 testing.
 
-In case that the in[number] of cells aren't in order you should go to the 
+In case that the in[number] of cells aren't in order you should go to the
 kernel in the toolbar and restart it.
 
 

docs/source/custom_resolvers.rst

@@ -156,7 +156,7 @@ Built-in resolvers
 
 .. _oc.env:
 
-oc.env 
+oc.env
 ^^^^^^
 
 Access to environment variables is supported using ``oc.env``:
@@ -176,7 +176,7 @@ Input YAML file:
 
 You can specify a default value to use in case the environment variable is not set.
 In such a case, the default value is converted to a string using ``str(default)``,
-unless it is ``null`` (representing Python ``None``) - in which case ``None`` is returned. 
+unless it is ``null`` (representing Python ``None``) - in which case ``None`` is returned.
 
 The following example falls back to default passwords when ``DB_PASSWORD`` is not defined:
 
@@ -221,7 +221,7 @@ oc.create
     ...         "dict_config_env": "${oc.create:${oc.env:YAML_ENV}}",
     ...     }
     ... )
-    >>> os.environ["YAML_ENV"] = "A: 10\nb: 20\nC: ${.A}" 
+    >>> os.environ["YAML_ENV"] = "A: 10\nb: 20\nC: ${.A}"
     >>> show(cfg.plain_dict)  # `make_dict` returns a Python dict
     type: dict, value: {'a': 10}
     >>> show(cfg.dict_config)  # `oc.create` converts it to DictConfig
@@ -246,11 +246,11 @@ It takes two parameters:
 .. doctest::
 
     >>> conf = OmegaConf.create({
-    ...   "rusty_key": "${oc.deprecated:shiny_key}", 
+    ...   "rusty_key": "${oc.deprecated:shiny_key}",
     ...   "custom_msg": "${oc.deprecated:shiny_key, 'Use $NEW_KEY'}",
     ...   "shiny_key": 10
     ... })
-    >>> # Accessing rusty_key will issue a deprecation warning 
+    >>> # Accessing rusty_key will issue a deprecation warning
     >>> # and return the new value automatically
     >>> warning = "'rusty_key' is deprecated. Change your" \
     ...           " code and config to use 'shiny_key'"
@@ -348,7 +348,7 @@ Another scenario where ``oc.select`` can be useful is if you want to select a mi
     ...         "with_default": "${oc.select:missing,default value}",
     ...     }
     ... )
-    ... 
+    ...
     >>> print(cfg.interpolation)
     Traceback (most recent call last):
     ...
@@ -391,3 +391,67 @@ as interpolations), and they return a ``ListConfig`` that contains keys or value
     >>> show(cfg.ips)
     type: ListConfig, value: ['${workers.node3}', '${workers.node7}']
     >>> assert cfg.ips == ["10.0.0.2", "10.0.0.9"]
+
+.. _clearing_resolvers:
+
+Clearing/removing resolvers
+---------------------------
+
+.. _clear_resolvers:
+
+clear_resolvers
+^^^^^^^^^^^^^^^
+
+Use ``OmegaConf.clear_resolvers()`` to remove all resolvers except the built-in resolvers (like ``oc.env`` etc).
+
+.. code-block:: python
+
+    def clear_resolvers() -> None
+
+In the following example, first we register a new custom resolver ``str.lower``, and then clear all
+custom resolvers.
+
+.. doctest::
+
+    >>> # register a new resolver: str.lower
+    >>> OmegaConf.register_new_resolver(
+    ...     name='str.lower',
+    ...     resolver=lambda x: str(x).lower(),
+    ... )
+    >>> # check if resolver exists (after adding, before removal)
+    >>> OmegaConf.has_resolver("str.lower")
+    True
+    >>> # clear all custom-resolvers
+    >>> OmegaConf.clear_resolvers()
+    >>> # check if resolver exists (after removal)
+    >>> OmegaConf.has_resolver("str.lower")
+    False
+    >>> # default resolvers are not affected
+    >>> OmegaConf.has_resolver("oc.env")
+    True
+
+.. _clear_resolver:
+
+clear_resolver
+^^^^^^^^^^^^^^
+
+Use ``OmegaConf.clear_resolver()`` to remove a single resolver (including built-in resolvers).
+
+.. code-block:: python
+
+    def clear_resolver(name: str) -> bool
+
+
+``OmegaConf.clear_resolver()`` returns True if the resolver was found and removed, and False otherwise.
+
+Here is an example.
+
+.. doctest::
+
+    >>> OmegaConf.has_resolver("oc.env")
+    True
+    >>> # This will remove the default resolver: oc.env
+    >>> OmegaConf.clear_resolver("oc.env")
+    True
+    >>> OmegaConf.has_resolver("oc.env")
+    False

omegaconf/omegaconf.py

@@ -467,6 +467,23 @@ def clear_resolvers() -> None:
         BaseContainer._resolvers = {}
         register_default_resolvers()
 
+    @classmethod
+    def clear_resolver(cls, name: str) -> bool:
+        """Clear(remove) any resolver only if it exists. Returns a bool: True if resolver is removed and False if not removed.
+
+        .. warning:
+            This method can remove deafult resolvers as well.
+
+        :param name: Name of the resolver.
+        :return: A bool (``True`` if resolver is removed, ``False`` if not found before removing).
+        """
+        if cls.has_resolver(name):
+            BaseContainer._resolvers.pop(name)
+            return True
+        else:
+            # return False if resolver does not exist
+            return False
+
     @staticmethod
     def get_cache(conf: BaseContainer) -> Dict[str, Any]:
         return conf._metadata.resolver_cache

tests/test_omegaconf.py

@@ -518,3 +518,42 @@ def test_resolve(cfg: Any, expected: Any) -> None:
 def test_resolve_invalid_input() -> None:
     with raises(ValueError):
         OmegaConf.resolve("aaa")  # type: ignore
+
+
+@mark.parametrize(
+    ("register_resolver_params", "name", "expected"),
+    [
+        param(
+            dict(
+                name="iamnew",
+                resolver=lambda x: str(x).lower(),
+                use_cache=False,
+                replace=False,
+            ),
+            "iamnew",
+            dict(pre_clear=True, result=True),
+            id="remove-new-custom-resolver",
+        ),
+        param(
+            dict(),
+            "oc.env",
+            dict(pre_clear=True, result=True),
+            id="remove-default-resolver",
+        ),
+        param(
+            dict(),
+            "idonotexist",
+            dict(pre_clear=False, result=False),
+            id="remove-nonexistent-resolver",
+        ),
+    ],
+)
+def test_clear_resolver(
+    restore_resolvers: Any, register_resolver_params: Any, name: str, expected: Any
+) -> None:
+    if register_resolver_params:
+        OmegaConf.register_new_resolver(**register_resolver_params)
+    assert expected["pre_clear"] == OmegaConf.has_resolver(name)
+
+    assert OmegaConf.clear_resolver(name) == expected["result"]
+    assert not OmegaConf.has_resolver(name)