bob at redivi.com
Wed Feb 22 18:04:38 CET 2006
On Feb 22, 2006, at 4:18 AM, Fuzzyman wrote:
> Raymond Hettinger wrote:
>>>>>> from operator import isSequenceType, isMappingType
>>>>>> class anything(object):
>>> ... def __getitem__(self, index):
>>> ... pass
>>>>>> something = anything()
>>> I suggest we either deprecate these functions as worthless, *or* we
>>> define the protocols slightly more clearly for user defined classes.
>> They are not worthless. They do a damned good job of differentiating
>> anything that CAN be differentiated.
> But as far as I can tell (and I may be wrong), they only work if the
> object is a subclass of a built in type, otherwise they're broken. So
> you'd have to do a type check as well, unless you document that an API
> call *only* works with a builtin type or subclass.
If you really cared, you could check hasattr(something, 'get') and
hasattr(something, '__getitem__'), which is a pretty good indicator
that it's a mapping and not a sequence (in a dict-like sense, anyway).
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