[Pyrex] exposing extension class attributes

[Robert Bradshaw]

On Mar 18, 2008, at 5:04 PM, Greg Ewing wrote:

> Simon Burton wrote:
>> Ie. the c attribute has an underscore in front of it, and
>> from python the attribute is without underscore.
>>
>> As this is likely to drive me moderately crazy (keeping track
>> of underscores) I am wondering how other people handle this issue ?
>
> Would calling it "c_foo" make you feel any better?
>
> I'm not sure what could be done to make this any easier,
> short of having some magic by which the same name refers
> to the C attribute in Pyrex and the Python property in
> Python. But you need to be able to refer to the property
> in Pyrex as well, so I can't see how that would work.
>
>> A similar problem occurs with methods. I gave up on duplicating  
>> every method
>> (a cdef version and a python version), and am just using python  
>> methods for now.
>
> Cython has a mechanism for making C methods callable from
> Python as well as Pyrex, but last I heard, the implementation
> is incorrect in the presence of overriding+inheritance, and
> the Cython people are unwilling to pay the performance cost
> required to make it work properly.

Overriding and inheritance work for cpdef methods exactly as they do  
in Python. This has a slight speed penalty (one dictionary lookup) in  
some cases, but in the most common case it is essentially as fast as  
a cdef method.

- Robert