[Cython] PEP 3135 -- New Super

[Vitja Makarov]

2011/7/7 mark florisson <markflorisson88 at gmail.com>

> On 6 July 2011 10:01, Vitja Makarov <vitja.makarov at gmail.com> wrote:
> > 2011/7/6 Stefan Behnel <stefan_ml at behnel.de>:
> >> Vitja Makarov, 06.07.2011 09:05:
> >>>
> >>> 2011/7/6 Stefan Behnel<stefan_ml at behnel.de>:
> >>>>
> >>>> Stefan Behnel, 05.07.2011 10:04:
> >>>>>
> >>>>> Vitja Makarov, 05.07.2011 09:17:
> >>>>>>
> >>>>>> 2011/7/5 Stefan Behnel:
> >>>>>>>
> >>>>>>> Vitja Makarov, 05.07.2011 08:21:
> >>>>>>>>
> >>>>>>>> I was thinking about implementing new super() with no arguments.
> >>>>>>>
> >>>>>>> http://trac.cython.org/cython_trac/ticket/696
> >>>>>>>
> >>>>>>>> The problem is where to store __class__, I see two options here:
> >>>>>>>>
> >>>>>>>> 1. Add func_class member to CyFunction, this way __class__ will be
> >>>>>>>> private and not visible for inner functions:
> >>>>>>>> 2. Put it into closure
> >>>>>>>
> >>>>>>> The second option has the advantage of requiring the field only
> when
> >>>>>>> super()
> >>>>>>> is used, whereas the first impacts all functions.
> >>>>>>>
> >>>>>>> I would expect that programs commonly have a lot more functions
> than
> >>>>>>> specifically methods that use a no-argument call to super(), so
> this
> >>>>>>> may
> >>>>>>> make a difference.
> >>>>>>>
> >>>>>>
> >>>>>> So, now classes are created the following way:
> >>>>>>
> >>>>>> class_dict = {}
> >>>>>> class_dict.foo = foo_func
> >>>>>> class = CreateClass(class_dict)
> >>>>>>
> >>>>>> So after class is created I should check its dict for CyFunction
> >>>>>> members (maybe only ones that actually require __class__)
> >>>>>> and set __class__:
> >>>>>>
> >>>>>> for value in class.__dict__.itervalues():
> >>>>>> if isinstance(value, CyFunction) and value.func_class is WantClass:
> >>>>>> value.func_class = class
> >>>>>>
> >>>>>> Btw, first way requires cyfunction signature change, it would accept
> >>>>>> cyfunction object as first argument.
> >>>>>
> >>>>> We currently pass the binding (i.e. owning) object, right?
> >>>>
> >>>> So, how would this work for methods? We need to pass the 'self' object
> >>>> there, which the CyFunction doesn't know. If anything, it only knows
> the
> >>>> class it was defined in, which doesn't help here.
> >>>
> >>> From PEP: "super() is equivalent to: super(__class__,<firstarg>)"
> >>
> >> I wasn't speaking of super(). What I meant, was: how do we pass 'self'
> when
> >> we pass the CyFunction object as the first argument?
> >>
> >
> >
> > Oh, ok. Now we pass closure or nothing in self. So method's self is
> > passed via tuple.
> > Instancemethod do this for us. Now CyFucntion uses PyCFunction_Call we
> > can override this and change signature of cyfunction to:
> >
> > PyObject func(CyFunction *func, PyObject *self, PyObject *args,
> > PyObject *kwargs);
> >
> > This way we should implement new instancemethod type.
>
> Would it be easier to make scope objects attributes of functions? Then
> you could still utilize PyCFunction_Call without needing to check the
> argument flags and such right?
>
>
Sure, scope object is already functions attribute now it's stored inside
self.
But, instancemethods desc_get builds new args tuple with self as first
element.
We can implement cython version of instance method and change method
signature a little bit.



-- 
vitja.
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