python 3 problem: how to convert an extension method into a class Method
Steven D'Aprano
steve+comp.lang.python at pearwood.info
Tue Feb 26 23:46:04 EST 2013
On Tue, 26 Feb 2013 17:21:16 +0000, Robin Becker wrote:
> In python 2 I was able to improve speed of reportlab using a C extension
> to optimize some heavily used methods.
>
> so I was able to do this
>
>
> class A:
> .....
> def method(self,...):
> ....
>
>
> try:
> from extension import c_method
> import new
> A.method = new.instancemethod(c_method,None,A)
> except:
> pass
Why are you suppressing and ignoring arbitrary errors here? That doesn't
sound good. Surely a better way would be:
import new
try:
from extension import c_method
except ImportError:
pass
else:
A.method = new.instancemethod(c_method, None, A)
> and if the try succeeds our method is bound as a class method ie is
> unbound and works fine when I call it.
>
> In python 3 this doesn't seem to work at all. In fact the new module is
> gone. The types.MethodType stuff doesn't seem to work.
I've never tried this with a function written in C, but for one written
in Python all you need is this:
A.method = c_method
Try that and see if it works with your function written in C. I expect
that it will, provided that the function is written as a method
descriptor. I don't know enough about C extensions to tell you how to do
that, sorry.
--
Steven
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