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bidict v0.15.0 Release Notes

Release Date: 2018-03-29 // about 6 years ago

  • Speedups and memory usage improvements ++++++++++++++++++++++++++++++++++++++

    • 👉 Use :ref:slots to speed up bidict attribute access and reduce memory usage. On Python 3, instantiating a large number of bidicts now uses ~57% the amount of memory that it used before, and on Python 2 only ~33% the amount of memory that it used before, in a simple but representative benchmark <https://github.com/jab/bidict/pull/56#issuecomment-368203591>__.

    • 👉 Use weakrefs to refer to a bidict's inverse internally, no longer creating a strong reference cycle. Memory for a bidict that you create can now be reclaimed in CPython as soon as you no longer hold any references to it, rather than having to wait for the next garbage collection. See the new :ref:addendum:Bidict Avoids Reference Cycles documentation. #24 <https://github.com/jab/bidict/issues/20>__

    • Make :func:bidict.BidictBase.__eq__ significantly more speed- and memory-efficient when comparing to a non-:class:dict :class:~collections.abc.Mapping. (Mapping.__eq__()\'s inefficient implementation will now never be used.) The implementation is now more reusable as well.

    • Make :func:bidict.OrderedBidictBase.__iter__ as well as equality comparison slightly faster for ordered bidicts.

    🛠 Minor Bugfixes ++++++++++++++

    • :func:~bidict.namedbidict now verifies that the provided keyname and valname are distinct, raising :class:ValueError if they are equal.

    • :func:~bidict.namedbidict now raises :class:TypeError if the provided base_type is not a :class:~bidict.BidirectionalMapping.

    • If you create a custom bidict subclass whose _fwdm_cls differs from its _invm_cls (as in the FwdKeySortedBidict example from the :ref:extending:Sorted Bidict Recipes), the inverse bidirectional mapping type (with _fwdm_cls and _invm_cls swapped) is now correctly computed and used automatically for your custom bidict's :attr:~bidict.BidictBase.inverse bidict.

    Miscellaneous +++++++++++++

    • Classes no longer have to provide an __inverted__ attribute to be considered virtual subclasses of :class:~bidict.BidirectionalMapping.

    • If :func:bidict.inverted is passed an object with an __inverted__ attribute, it now ensures it is :func:callable before returning the result of calling it.

    • :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 __repr_delegate__ instead (which may be overridden if needed), for better composability.

    Minor Breaking API Changes ++++++++++++++++++++++++++

    The following breaking changes are expected to affect few if any users.

    • Split back out the :class:~bidict.BidictBase class from :class:~bidict.frozenbidict and :class:~bidict.OrderedBidictBase from :class:~bidict.FrozenOrderedBidict, reverting the merging of these in 0.14.0. Having e.g. issubclass(bidict, frozenbidict) == True was confusing, so this change restores issubclass(bidict, frozenbidict) == False.

    See the updated :ref:other-bidict-types:Bidict Types Diagram and :ref:other-bidict-types:Polymorphism documentation.

    • 📇 Rename:

      • bidict.BidictBase.fwdm → ._fwdm
      • bidict.BidictBase.invm → ._invm
      • bidict.BidictBase.fwd_cls → ._fwdm_cls
      • bidict.BidictBase.inv_cls → ._invm_cls
      • bidict.BidictBase.isinv → ._isinv

    Though overriding _fwdm_cls and _invm_cls remains supported (see :doc:extending), this is not a common enough use case to warrant public names. Most users do not need to know or care about any of these.

    • The :attr:~bidict.RAISE, :attr:~bidict.OVERWRITE, and :attr:~bidict.IGNORE duplication policies are no longer available as attributes of :class:bidict.DuplicationPolicy, and can now only be accessed as attributes of the :mod:bidict module namespace, which was the canonical way to refer to them anyway. It is now no longer possible to create an infinite chain like DuplicationPolicy.RAISE.RAISE.RAISE...

    • 👉 Make bidict.pairs() and :func:bidict.inverted no longer importable from bidict.util, and now only importable from the top-level :mod:bidict module. (bidict.util was renamed bidict._util.)

    • Pickling ordered bidicts now requires at least version 2 of the pickle protocol. If you are using Python 3, :attr:pickle.DEFAULT_PROTOCOL is 3 anyway, so this will not affect you. However if you are using in Python 2, :attr:~pickle.DEFAULT_PROTOCOL is 0, so you must now explicitly specify the version in your :func:pickle.dumps calls, e.g. pickle.dumps(ob, 2).