[Pyrex] Pyrex optimization chitchat

[Phillip J. Eby]

At 02:27 PM 1/22/04 +1300, Greg Ewing wrote:
>Paul Prescod:
>
> > cdef x(list foo):
> >       foo.append(5)
> >
> > Should the compiler expand that to optimized PyList_Append code or call
> > a method by name?
>
>I think it really has to do a method lookup. Even if foo is
>declared to be a list, it might be a subclass of list that
>overrides the append method.

But what would be the point in declaring it a list, then?  :)

OTOH, how about:

cdef x(exact list foo):
    foo.append(5)

where 'exact' means that the type match uses PyList_CheckExact (or however 
it's spelled).  This would meet the use case of e.g.:

     cdef exact list items

     for x in something:
         items.append(x)

IOW, most of the places I use the direct Python APIs for performance are 
where I *know* I've got a list (or dictionary, or tuple), because I'm the 
one creating it, as either a local variable or a private attribute of an 
object.