Calling a Function From a String With the Function's Name in Python

Question

What is the best way to go about calling a function given a string with the function's name in a python program. For example, let's say that I have a module foo, and I have a string whose contents are "bar". What is the best way to go about calling foo.bar()?

I need to get the return value of the function, which is why I don't just use eval. I figured out how to do it by using eval to define a temp function that returns the result of that function call, but I'm hoping that there is a more elegant way to do this.

Answer 1

Well, there's:

string="bar"
exec"a=foo."+string+"()"

or maybe

exec "a=foo.%s()"%string

I'm not sure how much more elegant that is, however. But you'll be hardpressed to find a way to "execute" a string without exec or eval.

Answer 2

Assuming module 'foo' with method 'bar':

import foo
methodToCall = getattr(foo, 'bar')
result = methodToCall()

As far as that goes lines 2 and three can be compressed to:

result = getattr(foo, 'bar')()

if that makes more sense for your use case. You can use getattr in this fashion on class instance bound methods, module-level methods, classmethods... the list goes on.

Answer 3

Patrick's solution is probably the cleanest. If you need to dynamically pick up the module as well, you can import it like:

m = __import__ ('foo')
func = getattr(m,'bar')
func()

Answer 4

locals()["myfunction"]()

or

globals()["myfunction"]()

locals returns a dictionary with a current local symbol table. globals returns a dictionary with global symbol table.