[Python-Dev] Proposed Mixins for Wide Interfaces

[Raymond Hettinger]

How about adding some mixins to simplify the
implementation of some of the fatter interfaces?

class CompareMixin:
    """
    Given an __eq__ method in a subclass, adds a __ne__ method
    Given __eq__ and __lt__, adds !=, <=, >, >=.
    """

class MappingMixin:
    """
    Given __setitem__, __getitem__,  and keys,
    implements values, items, update, get, setdefault, len,
    iterkeys, iteritems, itervalues, has_key, and __contains__.

    If __delitem__ is also supplied, implements clear, pop,
    and popitem.

    Takes advantage of __iter__ if supplied (recommended).
    
    Takes advantage of __contains__ or has_key if supplied
    (recommended).
    """

The idea is to make it easier to implement these interfaces.
Also, if the interfaces get expanded, the clients automatically
updated.  


Raymond Hettinger