Boolean not changing value

Question

def shoot(self, limb):
    if not limb:
        pass
    else:
        limb = False    


print Joe.body.head #prints out true
Bob.gun.shoot(Joe.body.head) # should print out false
print Joe.body.head #prints out true (???)

I'm new to Python and am making a game as part of the LPTHW. My shoot function is supposed to disable a limb by setting it to false, but it doesn't edit the boolean at all. This might seem a bit redundant considering that I can set the boolean directly, but the shoot function will calculate a lot more than just changing a boolean. Help would be greatly appreciated.

Answer 1

Python passes its object references by value, so by doing limb = False you're assigning a new object reference with the value False to the parameter limb, not modifying the object originally held by the parameter. (Well, technically it's not a "new" reference, as I believe True, False, and None are all singletons in Python.)

Here's something that would work, however.

def shoot(self, other, limbstr):
    try:
        if getattr(other, limbstr):     # Levon's suggestion was a good one
            setattr(other, limbstr, False)
    except AttributeError:
        pass   # If the other doesn't have the specified attribute for whatever reason, then no need to do anything as the bullet will just pass by

Bob.gun.shoot(Joe.body, 'head')