itertools to iter transition (WAS: Pre-PEP: Dictionary accumulator methods)
tjreedy at udel.edu
Wed Mar 30 08:25:53 CEST 2005
"Steven Bethard" <steven.bethard at gmail.com> wrote in message
news:UvSdnQOHBJMWpNffRVn-sA at comcast.com...
> Terry Reedy wrote:
>> "Steven Bethard" <steven.bethard at gmail.com> wrote in message
>> news:t8GdnWcs-9J6AdTfRVn-hw at comcast.com...
>>>True it's not a huge win. But I'd argue that for the same reasons that
>>>dict.fromkeys is a dict classmethod, the itertools methods could be iter
>>>classmethods (or staticmethods).
>> As near as I could tell from the doc, .fromkeys is the only dict method
>> that is a classmethod (better, typemethod) rather than an instance
>> method. And all list methods are instance methods. And I believe the
>> same is true of all number operations (and the corresponding special
>> methods). So .fromkeys seems to be an anomaly.
>> I believe the reason for its existence is that the signature for dict()
>> itself was already pretty well 'used up' and Guido preferred to add an
>> alternate constructor as a method rather than further complicate the
>> signature of dict() by adding a fromkeys flag to signal an alternate
>> interpretation of the first and possibly the second parameter.
> True enough, and I also agree with George Sakkis's sentiment that
> fromkeys() isn't really necessary now that set() is a builtin.
So perhaps it will disappear in the future.
> But if classmethods are intended to provide alternate constructors
But I do not remember that being given as a reason for classmethod(). But
I am not sure what was.
Terry J. Reedy
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