Steven Bethard wrote:
> Note that even though the `Language Reference`_ defines mappings in
> terms of __len__, __getitem__, __setitem__, __delitem__ and __iter__,
> UserDict.DictMixin.update has to assume that all mappings have a
> .keys() method.
A slightly different proposal:
Add an iteritems() builtin with the following definition:
def iteritems(obj):
# Check for mapping first
try:
items = obj.items # or __items__ if you prefer
except AttributeError:
pass
else:
return iter(items())
# Check for sequence next
if hasattr(obj, "__getitem__"):
return enumerate(obj)
# Fall back on normal iteration
return iter(obj)
Then update the language reference so that the presence of of an items() (or
__items__()) method is the defining characteristic that makes something a
mapping instead of a sequence. After all, we've been trying to think of a way
to denote that anyway.
Cheers,
Nick.
--
Nick Coghlan | [EMAIL PROTECTED] | Brisbane, Australia
---------------------------------------------------------------
http://www.boredomandlaziness.org
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