Declaring A Function Argument As Global?

[Mark Jackson]

Tim Daneliuk <tundra at tundraware.com> writes:
> I want to be able to write a generic list handling function which slices
> a list, but I don't want to have to return the modified list
> to do so.  In other words, I purposely want the function to have
> a side-effect which modifies the list handed to it. For example:
> 
> 
> def lhandler(list):
> 	list = list[1:]
> 
> mylist = [1,2,3]
> 
> lhandler(mylist) doesn't change mylist (because the assignment creates
> a local variable by Python scoping rules), but that's exactly what
> I want it to do.  So far, I've only come up with two solutions:
> 
>           1) return the modified value - for various reasons, this is
>              an ugly solution in my application.
> 
>           2) Pass the *name* of the list into the function and do something
>              truly ugly like:
> 
>                  globals()[name] = globals()[name][1:]   # Yuk!
> 
> Is there another way?

def lhandler(list):
	list.remove(list[0])

modifies the list in place as required by the example given.  Rewriting
what you *actually* want to do using only in-place list methods may be
less straightforward or have performance implications, of course.

-- 
Mark Jackson - http://www.alumni.caltech.edu/~mjackson
	Well. . .old people with really good memories think I'm
	clever.  So there!!	- Huey Freeman (Aaron McGruder)