Calling a function dynamically

Eric Brunel eric.brunel at N0SP4M.com
Thu Jan 8 17:01:22 CET 2004


Paradox wrote:
> I would like to call a function whose name I supply at runtime.
> Something like this but it didn't work
> 
> functionName = 'run'
> instance = ClassDef()
> args = [1, 2]
> 
> #want the dynamic equivalant of
> #instance.run(*args)
> 
> #This didn't work cause there was no __call__ attribute. Why?
> value = instance.__call__[functionName](*args)

The "function" is in fact a method on the instance, that is handled like a 
regular attribute. So using getattr should do what you want:

value = getattr(instance, functionName)(*args)

__call__ is for a completely different purpose, which is to define instances 
that behave like functions:

 >>> class Spammer:
...     def __call__(self):
...             print 'spam'
...
 >>> o = Spammer()
 >>> o()
spam


HTH
-- 
- Eric Brunel <eric dot brunel at pragmadev dot com> -
PragmaDev : Real Time Software Development Tools - http://www.pragmadev.com




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