[Python-ideas] Syntactic sugar to declare partial functions

[Robert Vanden Eynde]

Le sam. 11 août 2018 à 10:34, Vincent Maillol <vincent.maillol at gmail.com> a
écrit :

> Hello,
>
> Currently the user defined functions are mutables, there can be existed
> python codes like this:
>
> >>> def foo():
> ...     pass
> ...
> >>> if not hasattr(foo, 'partial'):
> ...     foo.partial = {}
> ...
>
> Adding a new method to function object can break existing projects, but it
> is without impact with buit-in functions because they are immutables.
>
>
Or use a decorator like in the lib ?

from funcoperators import partially

@partially
def f(x, y):
    return x-y

g = f.part(4)
g(5)

The mutability solution however cannot have a "self" argument :

def f(x,y):
    return x-y

f.stuff = lambda self: self(5, 2)
f.stuff()  # missing self

One would have to give "f".

f.partial = lambda *a, **b: functools.partial(f, *a, **b)

g = f.partial(4)
g(5)


> 2018-08-09 18:59 GMT+02:00 Michel Desmoulin <desmoulinmichel at gmail.com>:
>
>> I'd rather have functools.partial() to be added as a new method on
>> function objects.
>>
>> >
>> > fromfunctools importpartial
>> >
>> >
>> > def add(x:int,y:int)->int:
>> >     returnx +y
>> >
>> >
>> > add_2 = partial(add,2)
>> >
>>
>> Would become:
>>
>> add_2 = add.partial(2)
>>
>> Nothing to change on the parser, no obscure syntax for future readers,
>> and we can get the opportunity of rewriting partial() in C as right now
>> it is amazingly way, way slower than a lambda.
>> _______________________________________________
>> Python-ideas mailing list
>> Python-ideas at python.org
>> https://mail.python.org/mailman/listinfo/python-ideas
>> Code of Conduct: http://python.org/psf/codeofconduct/
>>
>
> _______________________________________________
> Python-ideas mailing list
> Python-ideas at python.org
> https://mail.python.org/mailman/listinfo/python-ideas
> Code of Conduct: http://python.org/psf/codeofconduct/
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-ideas/attachments/20180811/75d4e9cf/attachment-0001.html>