resurrect delegating mixins instead of __delegate__ + other refinements

e.g. s/__repr_delegate__/_repr_delegate

Also
- update
- update from pytest 3 to 4
- add CII best practices badge
- prepare for 0.17.5 release

CHANGELOG.rst

@@ -22,6 +22,26 @@ Tip: `Subscribe to bidict releases <https://libraries.io/pypi/bidict>`__
 on libraries.io to be notified when new versions of bidict are released.
 
 
+0.17.5 (2018-11-19)
+-------------------
+
+Improvements to performance and delegation logic,
+with minor breaking changes to semi-private APIs.
+
+- Remove the ``__delegate__`` instance attribute added in the previous release.
+  It was overly general and not worth the cost.
+
+  Instead of checking ``self.__delegate__`` and delegating accordingly
+  each time a possibly-delegating method is called,
+  revert back to using "delegated-to-fwdm" mixin classes
+  (now found in ``bidict._delegating_mixins``),
+  and resurrect a mutable bidict parent class that omits the mixins
+  as :class:`bidict.MutableBidict`.
+
+- Rename ``__repr_delegate__`` to
+  :class:`~bidict.BidictBase._repr_delegate`.
+
+
 0.17.4 (2018-11-14)
 -------------------
 
@@ -39,8 +59,8 @@ Minor code, interop, and (semi-)private API improvements.
   and instead move their methods
   into :class:`~bidict.BidictBase`,
   which now checks for an object defined by the
-  :attr:`~bidict.BidictBase.__delegate__` attribute.
-  The :attr:`~bidict.BidictBase.__delegate__` object
+  ``BidictBase.__delegate__`` attribute.
+  The ``BidictBase.__delegate__`` object
   will be delegated to if the method is available on it,
   otherwise a default implementation
   (e.g. inherited from :class:`~collections.abc.Mapping`)
@@ -50,8 +70,8 @@ Minor code, interop, and (semi-)private API improvements.
   Consolidate ``_MutableBidict`` into :class:`bidict.bidict`
   now that the dropped mixin classes make it unnecessary.
 
-- Change :attr:`~bidict.BidictBase.__repr_delegate__`
-  to take simply a type like :class:`dict` or :class:`list`.
+- Change ``__repr_delegate__``
+  to simply take a type like :class:`dict` or :class:`list`.
 
 - Upgrade to latest major
   `sortedcontainers <https://github.com/grantjenks/python-sortedcontainers>`__
@@ -64,7 +84,7 @@ Minor code, interop, and (semi-)private API improvements.
   :class:`~collections.abc.Mapping` interface,
   and provides fallback implementations when the methods are unavailable.
   This allows the :ref:`extending:Sorted Bidict Recipes`
-  to continue to work with sortedcontainers v2 on Python2.
+  to continue to work with sortedcontainers v2 on Python 2.
 
 
 0.17.3 (2018-09-18)
@@ -221,7 +241,7 @@ Miscellaneous
 
 - :func:`~bidict.BidictBase.__repr__` no longer checks for a ``__reversed__``
   method to determine whether to use an ordered or unordered-style repr.
-  It now calls the new :attr:`~bidict.BidictBase.__repr_delegate__` instead
+  It now calls the new ``__repr_delegate__`` instead
   (which may be overridden if needed), for better composability.
 
 Minor Breaking API Changes

README.rst

@@ -41,6 +41,10 @@ Status
    :target: https://www.codacy.com/app/jab/bidict
    :alt: Codacy grade
 
+.. image:: https://bestpractices.coreinfrastructure.org/projects/2354/badge
+   :target: https://bestpractices.coreinfrastructure.org/en/projects/2354
+   :alt: CII best practices badge
+
 .. image:: https://tidelift.com/badges/github/jab/bidict
    :target: https://tidelift.com/subscription/pkg/pypi-bidict?utm_source=pypi-bidict&utm_medium=referral&utm_campaign=docs
    :alt: Tidelift dependency badge

assets/bidict-types-diagram.dot

@@ -1,4 +1,4 @@
-// Copyright 2018 Joshua Bronson. All Rights Reserved.
+// Copyright 2009-2018 Joshua Bronson. All Rights Reserved.
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this

assets/custom.css

@@ -1,5 +1,5 @@
 /*
- * Copyright 2018 Joshua Bronson. All Rights Reserved.
+ * Copyright 2009-2018 Joshua Bronson. All Rights Reserved.
  *
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this

bidict/__init__.py

@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-# Copyright 2018 Joshua Bronson. All Rights Reserved.
+# Copyright 2009-2018 Joshua Bronson. All Rights Reserved.
 #
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -44,6 +44,7 @@
 
 from ._abc import BidirectionalMapping
 from ._base import BidictBase
+from ._mut import MutableBidict
 from ._bidict import bidict
 from ._dup import DuplicationPolicy, IGNORE, OVERWRITE, RAISE
 from ._exc import (
@@ -84,6 +85,7 @@
     'ValueDuplicationError',
     'KeyAndValueDuplicationError',
     'BidictBase',
+    'MutableBidict',
     'frozenbidict',
     'bidict',
     'namedbidict',

bidict/_abc.py

@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-# Copyright 2018 Joshua Bronson. All Rights Reserved.
+# Copyright 2009-2018 Joshua Bronson. All Rights Reserved.
 #
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this

bidict/_base.py

@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-# Copyright 2018 Joshua Bronson. All Rights Reserved.
+# Copyright 2009-2018 Joshua Bronson. All Rights Reserved.
 #
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -22,7 +22,7 @@
 
 #                             * Code review nav *
 #==============================================================================
-#  ← Prev: _abc.py             Current: _base.py     Next: _frozenbidict.py →
+# ← Prev: _abc.py             Current: _base.py   Next: _delegating_mixins.py →
 #==============================================================================
 
 
@@ -38,7 +38,7 @@
 from ._miss import _MISS
 from ._noop import _NOOP
 from ._util import _iteritems_args_kw
-from .compat import PY2, KeysView, ItemsView, iteritems, Mapping
+from .compat import PY2, KeysView, ItemsView, Mapping, iteritems
 
 
 # Since BidirectionalMapping implements __subclasshook__, and BidictBase
@@ -52,10 +52,7 @@
 class BidictBase(BidirectionalMapping):
     """Base class implementing :class:`BidirectionalMapping`."""
 
-    __slots__ = ['_fwdm', '_invm', '_inv', '_invweak', '_hash']
-
-    if not PY2:
-        __slots__.append('__weakref__')
+    __slots__ = ('_fwdm', '_invm', '_inv', '_invweak', '_hash') + (() if PY2 else ('__weakref__',))
 
     #: The default :class:`DuplicationPolicy`
     #: (in effect during e.g. :meth:`~bidict.bidict.__init__` calls)
@@ -94,7 +91,7 @@ class BidictBase(BidirectionalMapping):
     _invm_cls = dict
 
     #: The object used by :meth:`__repr__` for printing the contained items.
-    __repr_delegate__ = dict
+    _repr_delegate = dict
 
     def __init__(self, *args, **kw):  # pylint: disable=super-init-not-called
         """Make a new bidirectional dictionary.
@@ -194,7 +191,7 @@ def __repr__(self):
         clsname = self.__class__.__name__
         if not self:
             return '%s()' % clsname
-        return '%s(%r)' % (clsname, self.__repr_delegate__(iteritems(self)))
+        return '%s(%r)' % (clsname, self._repr_delegate(iteritems(self)))
 
     # The inherited Mapping.__eq__ implementation would work, but it's implemented in terms of an
     # inefficient ``dict(self.items()) == dict(other.items())`` comparison, so override it with a
@@ -400,28 +397,16 @@ def __len__(self):
         """The number of contained items."""
         return len(self._fwdm)
 
-    @property
-    def __delegate__(self):
-        """An object to delegate to for optimized implementations
-        of various operations (e.g. :meth:`keys`) if available.
-        Override or set e.g. ``__delegate__ = None`` in a subclass to disable.
-        """
-        return self._fwdm
-
     def __iter__(self):  # lgtm [py/inheritance/incorrect-overridden-signature]
         """Iterator over the contained items."""
-        delegate = getattr(self.__delegate__, '__iter__', lambda: iter(self.keys()))
-        return delegate()
+        # No default implementation for __iter__ inherited from Mapping ->
+        # always delegate to _fwdm.
+        return iter(self._fwdm)
 
     def __getitem__(self, key):
         u"""*x.__getitem__(key)　⟺　x[key]*"""
         return self._fwdm[key]
 
-    def keys(self):
-        """A set-like object providing a view on the contained keys."""
-        delegate = getattr(self.__delegate__, 'keys', super(BidictBase, self).keys)
-        return delegate()
-
     def values(self):
         """A set-like object providing a view on the contained values.
 
@@ -434,18 +419,16 @@ def values(self):
         """
         return self.inv.keys()
 
-    def items(self):
-        """A set-like object providing a view on the contained items."""
-        delegate = getattr(self.__delegate__, 'items', super(BidictBase, self).items)
-        return delegate()
-
     if PY2:
-        def viewkeys(self):  # noqa: D102; pylint: disable=missing-docstring
-            delegate = getattr(self.__delegate__, 'viewkeys', lambda: KeysView(self))
-            return delegate()
+        # For iterkeys and iteritems, inheriting from Mapping already provides
+        # the best default implementations so no need to define here.
 
-        viewkeys.__doc__ = keys.__doc__
-        keys.__doc__ = 'A list of the contained keys.'
+        def itervalues(self):
+            """An iterator over the contained values."""
+            return self.inv.iterkeys()
+
+        def viewkeys(self):  # noqa: D102; pylint: disable=missing-docstring
+            return KeysView(self)
 
         def viewvalues(self):  # noqa: D102; pylint: disable=missing-docstring
             return self.inv.viewkeys()
@@ -454,25 +437,7 @@ def viewvalues(self):  # noqa: D102; pylint: disable=missing-docstring
         values.__doc__ = 'A list of the contained values.'
 
         def viewitems(self):  # noqa: D102; pylint: disable=missing-docstring
-            delegate = getattr(self.__delegate__, 'viewitems', lambda: ItemsView(self))
-            return delegate()
-
-        viewitems.__doc__ = items.__doc__
-        items.__doc__ = 'A list of the contained items.'
-
-        def iterkeys(self):
-            """An iterator over the contained keys."""
-            delegate = getattr(self.__delegate__, 'iterkeys', super(BidictBase, self).iterkeys)
-            return delegate()
-
-        def itervalues(self):
-            """An iterator over the contained values."""
-            return self.inv.iterkeys()
-
-        def iteritems(self):
-            """An iterator over the contained items."""
-            delegate = getattr(self.__delegate__, 'iteritems', super(BidictBase, self).iteritems)
-            return delegate()
+            return ItemsView(self)
 
         # __ne__ added automatically in Python 3 when you implement __eq__, but not in Python 2.
         def __ne__(self, other):  # noqa: N802
@@ -487,5 +452,5 @@ def __ne__(self, other):  # noqa: N802
 
 #                             * Code review nav *
 #==============================================================================
-#  ← Prev: _abc.py             Current: _base.py     Next: _frozenbidict.py →
+# ← Prev: _abc.py             Current: _base.py   Next: _delegating_mixins.py →
 #==============================================================================