[Python-ideas] Allow isinstance second argument to be a set of types
Masklinn
masklinn at masklinn.net
Tue Jul 5 08:23:22 CEST 2011
On 2011-07-05, at 06:32 , Stefan Behnel wrote:
> Raymond Hettinger, 05.07.2011 03:55:
>>
>> On Jul 4, 2011, at 6:26 PM, Greg Ewing wrote:
>>
>>> Chris Rebert wrote:
>>>
>>>> Why does it accept nested tuples in the first place for that matter?
>>>
>>> Probably so that tuples could be used to emulate a "set
>>> of types" before we had real sets.
>>>
>>> Now that we do have real sets, it doesn't seem necessary
>>> to continue with this and allow sets of sets, etc. So
>>> +1 on leaving tuple as a special case for this and
>>> treating all other iterables as flat.
>>
>> -1 on further garbaging this API by introducing yet another signature variant -- even worse, a signature variant with a special case for the tuple type (didn't we learn our lesson with old-style string formatting).
>>
>> I have to agree with Benjamin that this proposal would be utterly unnecessary software bloat.
>
> FWIW, another -1 from me. The current API is simple: you pass in either a type or a tuple of types.
Or a tuple of tuples of types. Or a tuple of tuple of tuple of types.
The actual API is something like this:
TypeSet = Type | [TypeSet]
isinstance :: (object, TypeSet) -> bool
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