[Cython] [cython-users] Re: New function (pointer) syntax.

[Robert Bradshaw]

On Thu, Nov 6, 2014 at 11:30 PM, Ian Henriksen
<insertinterestingnamehere at gmail.com> wrote:
> On Thursday, November 6, 2014 9:48:53 PM UTC-7, 1989lzhh wrote:
>>
>> > 在 Nov 7, 2014，02:56，Robert Bradshaw <robe... at gmail.com> 写道：
>> >
>> > [Cc'ing elsewhere for more feedback. Also top-posting for initial
>> > impressions before the discussion.]
>> >
>> > Here's some proposed function pointer syntaxes; which are the most
>> > obvious to understand/read/remember? Can you figure them out?
>> >
>> >    cdef float (*F)(float)
>> >    cdef float (*G)(float (*)(float), float, float)
>> >    cdef float ((*H)(char*))(float (*)(float), float, float)
>> >
>> > vs
>> >
>> >    cdef float -> float F
>> >    cdef (float -> float, float, float) -> float G
>> >    cdef (char*) -> (float -> float, float, float) -> float H
>> >
>> > vs
>> >
>> >    cdef lambda float: float F
>> >    cdef lambda (lambda float: float), float, float: float G
>> >    cdef lambda (char*): lambda: (lambda float: float), float, float:
>> > float H
>> >
>> >
>> > If you want a hint, the last is something that returns numerical
>> > integration algorithm given a string name. Yes, you could use
>> > typedefs, but you shouldn't have to. especially for the first.
>> >
>>    Here are numba kind function annotation, I guess it may fit in here.
>> cdef float(float) F
>> cdef float(float(float), float, float) G
>> cdef float(float(float), float, float)(char*) H
>> I personally feel this kind of annotation is more packed that using ->.
>>
>> Regards,
>> Liu zhenhai
>
>
> Here are my thoughts, for what they're worth.
> I actually really like the arrow syntax. It matches the way
> that the domains and ranges of functions are often written
> mathematically. On the other hand, it does conflict with
> the syntax from C.
>
> The syntax from Numba is a really good way to do this as well.
> It is just as clear and doesn't conflict with C. Strictly speaking,
> it isn't Python, but it would be nice to have similarities in the
> syntax for the different packages.
>
> The C syntax is not intuitive. The only benefit there is the
> overlap with C. For something this simple, learning the new
> syntax is easy enough.

+1

> The lambda syntax strikes me as an intuitive solution, but it
> isn't particularly clean or concise. If the syntax is going
> to change, it would be good to change it to something nicer
> than that. I don't think this one would be worth making the change.
>
> All things considered, the Numba syntax looks like the best idea.
> The arrows are intuitive as well, but the overlap with the syntax
> from C could be a bad thing.

Yeah, I'm kind of leaning that way too.

> Thanks for looking into this!

Thanks for the feedback.

- Robert