Re: python 3 problem: how to convert an extension method into a classMethod

Discussion in 'Python' started by Mark Lawrence, Feb 26, 2013.

  1. 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'

    --
    Cheers.

    Mark Lawrence
    Mark Lawrence, Feb 26, 2013
    #1
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. Robin Becker
    Replies:
    1
    Views:
    122
    Steven D'Aprano
    Feb 27, 2013
  2. Dave Angel
    Replies:
    0
    Views:
    113
    Dave Angel
    Feb 26, 2013
  3. Peter Otten
    Replies:
    0
    Views:
    110
    Peter Otten
    Feb 26, 2013
  4. Peter Otten
    Replies:
    0
    Views:
    122
    Peter Otten
    Feb 26, 2013
  5. Ethan Furman
    Replies:
    0
    Views:
    140
    Ethan Furman
    Feb 26, 2013
Loading...

Share This Page