Totally Confused: Passing variables to functions

[Dave Harrison]

Just as a side mention you might also be in a class,

in which case the 'global'  (read class-wide) variable
is accessed as self.variableName

being forced to reference with self is a useful bug stopper
if you want - for some reason - to have a local variable with the same
name as the global variable.

eg. where the global variable arg has been defined as 2

def foo(self, arg):
	return arg+self.arg

print 'Global : '+str(self.arg)
self.foo(2)
print 'Local plus Global : '+str(foo)


Michael Mayhew (mayhew at cis.ohio-state.edu):
> Howdy,
> 
>     To address the first problem, the following sample worked for me:
> 
> def blah(arg):
>      arg[:] = []
>      return arg
> 
> I think the reason is that using the slice operation, you are still, as you
> noticed, using methods on the "object reference" and so can change the
> mutable object in place.
> 
> For the second example, this sounds like a question of scope as v is
> declared in your global scope, but arg is local to the function. If you
> wanted to change v itself in the function blah, you would write
> 
> def blah():
>     global v
>     v = v + 1
> 
> v = 1
> blah()
> Now v equals 2!
> 
> If you wanted to simply change the local function reference to v, you would
> have to return the result and assign it to v, like so:
> 
> def blah(arg):
>     arg = arg+1
>     return arg
> 
> v = blah(v)
> Now v equals 2!
> 
> 
> I hope this helps somewhat,
> 
> Michael
> 
> 
> 
> 
> -- 
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