Merge pull request #588 from jaraco/feature/jaraco.classes

Use jaraco.classes for properties

keyring/_compat.py

@@ -0,0 +1,7 @@
+__all__ = ['properties']
+
+
+try:
+    from jaraco.compat import properties  # pragma: no-cover
+except ImportError:
+    from . import _properties_compat as properties  # pragma: no-cover

keyring/_properties_compat.py

@@ -0,0 +1,169 @@
+# from jaraco.classes 3.2.2
+
+
+class NonDataProperty:
+    """Much like the property builtin, but only implements __get__,
+    making it a non-data property, and can be subsequently reset.
+
+    See http://users.rcn.com/python/download/Descriptor.htm for more
+    information.
+
+    >>> class X(object):
+    ...   @NonDataProperty
+    ...   def foo(self):
+    ...     return 3
+    >>> x = X()
+    >>> x.foo
+    3
+    >>> x.foo = 4
+    >>> x.foo
+    4
+    """
+
+    def __init__(self, fget):
+        assert fget is not None, "fget cannot be none"
+        assert callable(fget), "fget must be callable"
+        self.fget = fget
+
+    def __get__(self, obj, objtype=None):
+        if obj is None:
+            return self
+        return self.fget(obj)
+
+
+class classproperty:
+    """
+    Like @property but applies at the class level.
+
+
+    >>> class X(metaclass=classproperty.Meta):
+    ...   val = None
+    ...   @classproperty
+    ...   def foo(cls):
+    ...     return cls.val
+    ...   @foo.setter
+    ...   def foo(cls, val):
+    ...     cls.val = val
+    >>> X.foo
+    >>> X.foo = 3
+    >>> X.foo
+    3
+    >>> x = X()
+    >>> x.foo
+    3
+    >>> X.foo = 4
+    >>> x.foo
+    4
+
+    Setting the property on an instance affects the class.
+
+    >>> x.foo = 5
+    >>> x.foo
+    5
+    >>> X.foo
+    5
+    >>> vars(x)
+    {}
+    >>> X().foo
+    5
+
+    Attempting to set an attribute where no setter was defined
+    results in an AttributeError:
+
+    >>> class GetOnly(metaclass=classproperty.Meta):
+    ...   @classproperty
+    ...   def foo(cls):
+    ...     return 'bar'
+    >>> GetOnly.foo = 3
+    Traceback (most recent call last):
+    ...
+    AttributeError: can't set attribute
+
+    It is also possible to wrap a classmethod or staticmethod in
+    a classproperty.
+
+    >>> class Static(metaclass=classproperty.Meta):
+    ...   @classproperty
+    ...   @classmethod
+    ...   def foo(cls):
+    ...     return 'foo'
+    ...   @classproperty
+    ...   @staticmethod
+    ...   def bar():
+    ...     return 'bar'
+    >>> Static.foo
+    'foo'
+    >>> Static.bar
+    'bar'
+
+    *Legacy*
+
+    For compatibility, if the metaclass isn't specified, the
+    legacy behavior will be invoked.
+
+    >>> class X:
+    ...   val = None
+    ...   @classproperty
+    ...   def foo(cls):
+    ...     return cls.val
+    ...   @foo.setter
+    ...   def foo(cls, val):
+    ...     cls.val = val
+    >>> X.foo
+    >>> X.foo = 3
+    >>> X.foo
+    3
+    >>> x = X()
+    >>> x.foo
+    3
+    >>> X.foo = 4
+    >>> x.foo
+    4
+
+    Note, because the metaclass was not specified, setting
+    a value on an instance does not have the intended effect.
+
+    >>> x.foo = 5
+    >>> x.foo
+    5
+    >>> X.foo  # should be 5
+    4
+    >>> vars(x)  # should be empty
+    {'foo': 5}
+    >>> X().foo  # should be 5
+    4
+    """
+
+    class Meta(type):
+        def __setattr__(self, key, value):
+            obj = self.__dict__.get(key, None)
+            if type(obj) is classproperty:
+                return obj.__set__(self, value)
+            return super().__setattr__(key, value)
+
+    def __init__(self, fget, fset=None):
+        self.fget = self._ensure_method(fget)
+        self.fset = fset
+        fset and self.setter(fset)
+
+    def __get__(self, instance, owner=None):
+        return self.fget.__get__(None, owner)()
+
+    def __set__(self, owner, value):
+        if not self.fset:
+            raise AttributeError("can't set attribute")
+        if type(owner) is not classproperty.Meta:
+            owner = type(owner)
+        return self.fset.__get__(None, owner)(value)
+
+    def setter(self, fset):
+        self.fset = self._ensure_method(fset)
+        return self
+
+    @classmethod
+    def _ensure_method(cls, fn):
+        """
+        Ensure fn is a classmethod or staticmethod.
+        """
+        needs_method = not isinstance(fn, (classmethod, staticmethod))
+        return classmethod(fn) if needs_method else fn

keyring/backend.py

@@ -12,7 +12,7 @@
 
 from .py310compat import metadata
 from . import credentials, errors, util
-from .util import properties
+from ._compat import properties
 
 log = logging.getLogger(__name__)
 
@@ -61,8 +61,7 @@ def priority(cls):
         suitable, but a priority of one or greater is recommended.
         """
 
-    @properties.ClassProperty
-    @classmethod
+    @properties.classproperty
     def viable(cls):
         with errors.ExceptionRaisedContext() as exc:
             cls.priority
@@ -75,8 +74,7 @@ def get_viable_backends(cls):
         """
         return filter(operator.attrgetter('viable'), cls._classes)
 
-    @properties.ClassProperty
-    @classmethod
+    @properties.classproperty
     def name(cls):
         """
         The keyring name, suitable for display.

keyring/backends/SecretService.py

@@ -2,7 +2,7 @@
 import logging
 
 from .. import backend
-from ..util import properties
+from .._compat import properties
 from ..backend import KeyringBackend
 from ..credentials import SimpleCredential
 from ..errors import (
@@ -29,8 +29,7 @@ class Keyring(backend.SchemeSelectable, KeyringBackend):
 
     appid = 'Python keyring library'
 
-    @properties.ClassProperty
-    @classmethod
+    @properties.classproperty
     def priority(cls):
         with ExceptionRaisedContext() as exc:
             secretstorage.__name__

keyring/backends/Windows.py

@@ -1,6 +1,6 @@
 import logging
 
-from ..util import properties
+from .._compat import properties
 from ..backend import KeyringBackend
 from ..credentials import SimpleCredential
 from ..errors import PasswordDeleteError, ExceptionRaisedContext
@@ -80,8 +80,7 @@ class WinVaultKeyring(KeyringBackend):
 
     persist = Persistence()
 
-    @properties.ClassProperty
-    @classmethod
+    @properties.classproperty
     def priority(cls):
         """
         If available, the preferred backend on Windows.

keyring/backends/chainer.py

@@ -4,7 +4,7 @@
 """
 
 from .. import backend
-from ..util import properties
+from .._compat import properties
 from . import fail
 
 
@@ -18,8 +18,7 @@ class ChainerBackend(backend.KeyringBackend):
     # until other backends have been constructed
     viable = True
 
-    @properties.ClassProperty
-    @classmethod
+    @properties.classproperty
     def priority(cls):
         """
         If there are backends to chain, high priority
@@ -28,8 +27,7 @@ def priority(cls):
         """
         return 10 if len(cls.backends) > 1 else (fail.Keyring.priority - 1)
 
-    @properties.ClassProperty
-    @classmethod
+    @properties.classproperty
     def backends(cls):
         """
         Discover all keyrings for chaining.

keyring/backends/kwallet.py

@@ -6,7 +6,7 @@
 from ..credentials import SimpleCredential
 from ..errors import PasswordDeleteError
 from ..errors import PasswordSetError, InitError, KeyringLocked
-from ..util import properties
+from .._compat import properties
 
 try:
     import dbus
@@ -37,8 +37,7 @@ class DBusKeyring(KeyringBackend):
     bus_name = 'org.kde.kwalletd5'
     object_path = '/modules/kwalletd5'
 
-    @properties.ClassProperty
-    @classmethod
+    @properties.classproperty
     def priority(cls):
         if 'dbus' not in globals():
             raise RuntimeError('python-dbus not installed')
@@ -161,7 +160,6 @@ class DBusKeyringKWallet4(DBusKeyring):
     bus_name = 'org.kde.kwalletd'
     object_path = '/modules/kwalletd'
 
-    @properties.ClassProperty
-    @classmethod
+    @properties.classproperty
     def priority(cls):
         return super().priority - 1

keyring/backends/libsecret.py

@@ -1,7 +1,7 @@
 import logging
 
 from .. import backend
-from ..util import properties
+from .._compat import properties
 from ..backend import KeyringBackend
 from ..credentials import SimpleCredential
 from ..errors import (
@@ -48,8 +48,7 @@ def schema(self):
     def collection(self):
         return Secret.COLLECTION_DEFAULT
 
-    @properties.ClassProperty
-    @classmethod
+    @properties.classproperty
     def priority(cls):
         with ExceptionRaisedContext() as exc:
             Secret.__name__

keyring/backends/macOS/__init__.py

@@ -7,7 +7,7 @@
 from ...errors import PasswordDeleteError
 from ...errors import KeyringLocked
 from ...errors import KeyringError
-from ...util import properties
+from ..._compat import properties
 
 try:
     from . import api
@@ -21,8 +21,7 @@ class Keyring(KeyringBackend):
     keychain = os.environ.get('KEYCHAIN_PATH')
     "Path to keychain file, overriding default"
 
-    @properties.ClassProperty
-    @classmethod
+    @properties.classproperty
     def priority(cls):
         """
         Preferred for all macOS environments.