Python: How to Init a Function by Calling It Using a String

This topic is an interesting one that I have faced on a few occasions. There are a couple of different solution that I have found over the last couple of years that work depending on the situation. So let’s back up again and state the problem in the form of a question.

“How do you call a function in python guven a string of the functions name?”

Generally this behavior is not allowed due to the strict type casting of python, ie. a function must be a function type before being able to call. So how do you approach calling a function by using a string? *note that both of these examples are assuming that the functions being called are residing within imported modules.

Here are a couple of examples:

1.) Use the getattr() built-in function to evaluate a module object and provide a string attribute denoting the name of the function to execute. *note This method is generally frowned upon as using getattr and eval are both possibly dangerous built in functions that can lead to security issues / unexpected results.

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import foo # Your module

methodCall = getattr(foo, 'bar')

result = methodCall()

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class Registry(object):

  def __init__(self):
    self.funcs = {}

  def execute(self, func):
    self.funcs[func.__name__] = func
    return func

  def dispatch(self, name, *args, **kwargs):
    try:
      return self.funcs[name](*args, **kwargs)
    except Exception as e:
      raise Error(e)

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import registry

callme = registry.Register()

@callme.execute
def myCoolFunction():
  print 'hello world'

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import myfuncs

runfunc = myfuncs.callme

runfunc.dispatch('myCoolFunction')