[Core] Added enum meta class (#16316)

sdk/core/azure-core/CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Features
 
+- Added `CaseInsensitiveEnumMeta` class for case-insensitive enums.  #16316
 - Add `raise_for_status` method onto `HttpResponse`. Calling `response.raise_for_status()` on a response with an error code
 will raise an `HttpResponseError`. Calling it on a good response will do nothing  #16399
 

sdk/core/azure-core/README.md

@@ -148,6 +148,20 @@ class MatchConditions(Enum):
     IfMissing = 5
 ```
 
+#### CaseInsensitiveEnumMeta
+
+A metaclass to support case-insensitive enums.
+```python
+from enum import Enum
+from six import with_metaclass
+
+from azure.core import CaseInsensitiveEnumMeta
+
+class MyCustomEnum(with_metaclass(CaseInsensitiveEnumMeta, str, Enum)):
+    FOO = 'foo'
+    BAR = 'bar'
+```
+
 ## Contributing
 This project welcomes contributions and suggestions. Most contributions require
 you to agree to a Contributor License Agreement (CLA) declaring that you have

sdk/core/azure-core/azure/core/__init__.py

@@ -29,11 +29,13 @@
 
 from ._pipeline_client import PipelineClient
 from ._match_conditions import MatchConditions
+from ._enum_meta import CaseInsensitiveEnumMeta
 
 
 __all__ = [
     "PipelineClient",
-    "MatchConditions"
+    "MatchConditions",
+    "CaseInsensitiveEnumMeta"
 ]
 
 try:

sdk/core/azure-core/azure/core/_enum_meta.py

@@ -0,0 +1,61 @@
+# --------------------------------------------------------------------------
+#
+# Copyright (c) Microsoft Corporation. All rights reserved.
+#
+# The MIT License (MIT)
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the ""Software""), to
+# deal in the Software without restriction, including without limitation the
+# rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+# sell copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED *AS IS*, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+# IN THE SOFTWARE.
+#
+# --------------------------------------------------------------------------
+
+from enum import EnumMeta
+
+
+class CaseInsensitiveEnumMeta(EnumMeta):
+    """Enum metaclass to allow for interoperability with case-insensitive strings.
+
+    Consuming this metaclass in an SDK should be done in the following manner:
+
+    .. code-block:: python
+
+        from enum import Enum
+        from six import with_metaclass
+        from azure.core import CaseInsensitiveEnumMeta
+
+        class MyCustomEnum(with_metaclass(CaseInsensitiveEnumMeta, str, Enum)):
+            FOO = 'foo'
+            BAR = 'bar'
+
+    """
+
+    def __getitem__(cls, name):
+        # disabling pylint bc of pylint bug https://github.com/PyCQA/astroid/issues/713
+        return super(CaseInsensitiveEnumMeta, cls).__getitem__(name.upper())  # pylint: disable=no-value-for-parameter
+
+    def __getattr__(cls, name):
+        """Return the enum member matching `name`
+        We use __getattr__ instead of descriptors or inserting into the enum
+        class' __dict__ in order to support `name` and `value` being both
+        properties for enum members (which live in the class' __dict__) and
+        enum members themselves.
+        """
+        try:
+            return cls._member_map_[name.upper()]
+        except KeyError:
+            raise AttributeError(name)

sdk/core/azure-core/tests/test_enums.py

@@ -0,0 +1,44 @@
+# --------------------------------------------------------------------------
+#
+# Copyright (c) Microsoft Corporation. All rights reserved.
+#
+# The MIT License (MIT)
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the ""Software""), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED *AS IS*, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+#
+# --------------------------------------------------------------------------
+from enum import Enum
+from six import with_metaclass
+
+from azure.core import CaseInsensitiveEnumMeta
+
+class MyCustomEnum(with_metaclass(CaseInsensitiveEnumMeta, str, Enum)):
+    FOO = 'foo'
+    BAR = 'bar'
+
+
+def test_case_insensitive_enums():
+    assert MyCustomEnum.foo.value == 'foo'
+    assert MyCustomEnum.FOO.value == 'foo'
+    assert MyCustomEnum('bar').value == 'bar'
+    assert 'bar' == MyCustomEnum.BAR
+    assert 'bar' == MyCustomEnum.bar
+    assert MyCustomEnum['foo'] == 'foo'
+    assert MyCustomEnum['FOO'] == 'foo'
+    assert isinstance(MyCustomEnum.BAR, str)