[Tutor] Ask a class for it's methods
alan.gauld at btinternet.com
Sat Dec 13 00:41:38 CET 2008
"Shrutarshi Basu" <technorapture at gmail.com> wrote
>I have a list containing strings like :
> I want to turn them into method calls (with numeric or string
> arguments) on a supplied object.
The easiest way is to call getattr() which will return a reference
to the method if it exists.
> be rather complex (mainly graphics manipulation) I would like to
> by getting a list of the object's methods and make sure that all the
> strings are valid.
Why not just handle it using try/except?
Thats exactly what exceptions were designed for.
> Is there a way to ask an object for a list of it's
> methods (with argument requirements if possible)?
You can try dir() but that won't give you the parameters.
But again try/except can catch an invalid call and you can detect
whether the number of parameters is wrong in the except clause.
> method name (say func1) in a variable, say var, could I do
> object.var() and have if call the func1 method in object?
no, but you can do this:
>>> class C:
... def f(self, x): print x
>>> c = C()
['__doc__', '__module__', 'f']
>>> m = getattr(c,'f')
>>> try: m(43,'foo')
... except TypeError:
... # parse the error message here
... print 'Method of', c, 'takes ??? arguments'
Method of <__main__.C instance at 0x01BF8350> takes ??? arguments
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