mapping a string to an instancemethod

[attn.steven.kuo at gmail.com]

On Aug 1, 11:22 am, m... at pixar.com wrote:
> The following bit of code will allow an instance member to
> be called by reference.  How can I map a string (e.g.
> "hello1" or "Foo.hello1" to a the instance member?
>
> class Foo:
>     def hello1(self, p):
>         print 'hello1', p
>     def hello2(self, p):
>         print 'hello2', p
>     def dispatch(self, func, p):
>         func(self,p)
>
> f=Foo()
> f.dispatch(Foo.hello1, 23)
> f.dispatch(Foo.hello1, 24)
>
> f.dispatch_as_string("hello1", 23)  ## this is what I want to do.
>
> Many TIA and apologies if this is a FAQ, I googled and couldn't
> find the answer.



Use getattr; add exception handling as needed.  E.g.,


class Foo(object):
    def __init__(self):
        self.fake = None
    def hello1(self, p):
        print 'hello1', p
    def hello2(self, p):
        print 'hello2', p
    def dispatch_as_string(self, fname, p):
        try:
            inst_method=getattr(self, fname)
            inst_method(p)
        except AttributeError:
            # maybe no such attribute
            raise
        except TypeError:
            # maybe the attribute is not callable (wrong type)
            raise


f = Foo()
f.dispatch_as_string('hello1', 12)

--
Hope this helps,
Steven