optional flag in a function

Question

I would like to be able to pass extra arguments to a function and IF they are present then act accordingly (say print something out from the function), if those flags are not present, just execute the function normally without printing extra info, how would I approach this ?

Cheers

Answer 1

Let's say x, y and z are the required argruments and opt is optional:

def f(x, y, z, opt=None):
  # do required stuff
  if opt is not None:
    # do optional stuff

This can be called with either three or four arguments. You get the idea.

Answer 2

You could use also keyword arguments:

def f(x, y, **kwargs):
    if 'debug_output' in kwargs:
        print 'Debug output'

Then you can have as many as you like..

f(1,2, debug_output=True, file_output=True)