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 > > 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.
Hm, according to my random measurement your clever approach incurs more overhead than the straight-forward way that continues to work in Python 3: $ python -m timeit -s 'from new import instancemethod > from math import sqrt > class A(int): pass > A.m = instancemethod(sqrt, None, A) > a = A(42) > ' 'a.m()' 1000000 loops, best of 3: 0.5 usec per loop $ python -m timeit -s 'from math import sqrt > class A(int): > def m(self): > return sqrt(self) > a = A(42) > ' 'a.m()' 1000000 loops, best of 3: 0.473 usec per loop -- http://mail.python.org/mailman/listinfo/python-list