python 3 problem: how to convert an extension method into a class Method
davea at davea.name
Tue Feb 26 18:52:30 CET 2013
On 02/26/2013 12:21 PM, 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:
That creates an old-style class in Python 2.x. They've been obsolete
for many years. You want to derive from object:
Once you do, Python 2 and Python 3 should work the same. I can't help
with the rest, unfortunately.
> def method(self,...):
> from extension import c_method
> import new
> 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.
> Is there a way in Python 3.3 to make this happen? This particular method
> is short, but is called many times so adding python wrapping layers is
> not a good way forward.
> If the above cannot be made to work (another great victory for Python 3)
> then is there a way to bind an external method to the instance without
> incurring too much overhead.
> Alternatively could it make sense to implement an accelerated basetype
> that just contains the accelerated methods of class A. I could then
> imagine doing something like
> from extension import class c_baseA as baseA
> class baseA:
> def method(....)
> class A(baseA):
> presumably I then get some kind of penalty for the base class lookup,
> but how bad is that?
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