[Python-Dev] pep 362 - 5th edition

[Yury Selivanov]

On 2012-06-19, at 9:22 PM, Yury Selivanov wrote:
> On 2012-06-19, at 8:39 PM, Nick Coghlan wrote:
>> 7. The idea of immutable Signature objects does highlight an annoyance
>> with the "attribute may be missing" style APIs. To actually duplicate
>> a signature correctly, including its return annotation (and assuming
>> the attribute is renamed), you would have to do something like:
>> 
>>   try:
>>       note = {"annotation": old_sig.annotation}
>>   except AttributeError:
>>       note = {}
>>   new_sig = Signature(old_sig.parameters[1:], **note)

BTW, we don't have slices for OrderedDict.  Since the slice object is
not hashable, we can implement it safely.  I can create an issue (and draft
implementation), as I think it'd be quite a useful feature.

-
Yury