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[Python-Dev] PEP 457: Syntax For Positional-Only Parameters

Larry Hastings larry at hastings.org
Wed Oct 9 19:05:36 CEST 2013 
On 10/09/2013 06:48 PM, Terry Reedy wrote:
> On 10/9/2013 9:51 AM, Larry Hastings wrote:
>
>> range() in
>> PyPy accepts keyword parameters, and in fact this works:
>>
>>     range(9, step=2)
>>
>> That's way illegal in CPython.
>
> But Georg's point is that it does not have to be illegal in CPython. 
> Range, in particular, does not have to be blazingly fast since it 
> wraps loops rather than being in loops. I quite agree that it would be 
> better to fix most functions.

First, if you're proposing to change the signature of range()... well, 
good luck.  Any proposals I made like that got shot down almost 
immediately.  I /think/ Guido said somewhere "range isn't changing.  
deal with it.", though I admit I don't have a reference for that handy.

Also, if you're suggesting "change the semantics of builtins to get rid 
of positional-only parameters",  I've got a different example for you: 
the dict constructor, which /must/ accept a single optional 
positional-only parameter.  The only way to simulate that in Python code 
is with *args, but now introspection on that function will be 
misleading, because the dict constructor doesn't accept more than one 
positional-only argument.

And, as Georg suggests, these niggling inconsistencies are the 
hobgoblins of my small mind.


//arry/
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