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Calling a function of a module by using its name (a string)

Calling a function of a module by using its name (a string)

"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 content is ""bar"". What is the best way to call 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."

Asked by: Guest | Views: 77
Total answers/comments: 4
Guest [Entry]

"Assuming module foo with method bar:

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

You could shorten lines 2 and 3 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, class methods... the list goes on."
Guest [Entry]

"locals()[""myfunction""]()

or

globals()[""myfunction""]()

locals returns a dictionary with a current local symbol table. globals returns a dictionary with global symbol table."
Guest [Entry]

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

module = __import__('foo')
func = getattr(module, 'bar')
func()"
Guest [Entry]

"Just a simple contribution. If the class that we need to instance is in the same file, we can use something like this:

# Get class from globals and create an instance
m = globals()['our_class']()

# Get the function (from the instance) that we need to call
func = getattr(m, 'function_name')

# Call it
func()

For example:

class A:
def __init__(self):
pass

def sampleFunc(self, arg):
print('you called sampleFunc({})'.format(arg))

m = globals()['A']()
func = getattr(m, 'sampleFunc')
func('sample arg')

# Sample, all on one line
getattr(globals()['A'](), 'sampleFunc')('sample arg')

And, if not a class:

def sampleFunc(arg):
print('you called sampleFunc({})'.format(arg))

globals()['sampleFunc']('sample arg')"