[Cython] Bindings performance issue

[Vitja Makarov]

2011/6/2 Robert Bradshaw <robertwb at math.washington.edu>:
>> Initially bindings was written to support bound class methods (am I right?)
>> So when we use it for regular functions 'binding' in the name doesn't
>> reflect its purpose.
>
> There's three kinds of functions we create: PyCFunctions, binding
> PyCFunctions, and extension class methods (via descriptors). I was
> asking about the latter.
>
> As for the first two, it reflects the difference in behavior. If I
> take the function and assign it to a class, it will bind as a method
> when I go to look it up. This is arguably the biggest difference
> between built-in functions and Python functions.
>
>> One the other hand it's much more easy to write manually.
>>
>> About staticmethods: I think that CyFunction type should handle it as well
>> because staticmethods can have custom attributes and act just like
>> normal def one.
>>
>> The difference is insde descr_get it should return bound method for
>> normal and self for staticmethods.
>
> Yep. Does that merit a new class, or a flag that's checked on every
> function invocation (false 99.9% of the time)?
>

tp_descr_get() is called each time function gets bound, isn't so?
If it makes sens we can create both CyFunction and CyStaticFunction types.

>> Here I've tried to support staticmethods inside bindings type:
>> https://github.com/vitek/cython/commit/c0725ab340a8173d8e6724c62be3a135df58980e
>>
>>>
>>> I think that small speed regression for better compatibility is OK if
>>> we add a directive to not create binding functions. (It'd be nice if
>>> we could work around it, but that's hard as CPython has special
>>> hooks...) The bigger issue is that the binding behavior is backwards
>>> incompatible, and perhaps in a subtle way. Perhaps we need to have a
>>> phase where all currently non-binding functions that will become
>>> binding functions will raise an error (or at least a warning) to wean
>>> people off of the old behavior before making a switch.
>>>
>>
>> Is the difference so significant?
>
> If anyone is assigning a Cython function to an object and then using
> it they're counting on the current non-binding behavior, and it will
> break. The speed is probably a lesser issue, which is what benchmarks
> are for.
>




-- 
vitja.