jeanmichel at sequans.com
Thu Mar 1 14:46:43 CET 2012
Rolf Wester wrote:
> I would like to define methods using exec like this:
> class A:
> def __init__(self):
> cmd = "def sqr(self, x):\n return x**2\nself.sqr = sqr\n"
> exec cmd
> a = A()
> print a.sqr(a, 2)
> This works, but I have to call sqr with a.sqr(a, 2), a.sqr(2) does not work
> (TypeError: sqr() takes exactly 2 arguments (1 given)).
> Is there a possibility to define methods using exec and getting normal behavior?
> I would be very appreciative for any help.
> With kind regards
> Rolf Wester
I'll try to ignore you are using the exec statement which is an error :o)
a.sqr(2) would have worked only if sqr was a *bound* method.
<function sqr at 0x94ecd14>
to oppose to
<bound method A.__init__ of <__main__.A instance at 0x948734c>>
You cannot dynamically bind a method, however you can do the following.
cmd = "def sqr(x):\n return x**2\nself.sqr = sqr\n"
http://docs.python.org/reference/datamodel.html : <http://docs.python.org/reference/datamodel.html>
"It is also important to note that user-defined functions which are attributes of a class instance are not converted bound methods; this only happens when the function is an attribute of the class. "
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