Mark Lawrence wrote: > On 26/02/2013 18:38, Peter Otten wrote: >> 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 >> >> > > c:\Users\Mark\MyPython>python > Python 3.3.0 (v3.3.0:bd8afb90ebf2, Sep 29 2012, 10:55:48) [MSC v.1600 32 > bit (Intel)] on win32 > Type "help", "copyright", "credits" or "license" for more information. > >>> import new > Traceback (most recent call last): > File "<stdin>", line 1, in <module> > ImportError: No module named 'new'
I did the timing in Python 2 of course, to demonstrate that the feature the OP is missing in Python 3 offers no advantage in the Python version where it /is/ available. Does my previous post make sense now? -- http://mail.python.org/mailman/listinfo/python-list
