[Tutor] Passing values of a list as arguments

[Danny Yoo]

On Fri, 23 Nov 2001, lonetwin wrote:

> Hi all,
>     I just can't figure out to do this:
> ====================
> def somefunc(arg1, arg2=None)
>     if not arg2:
>         arg2 = someOtherValue
>     ....
>     ....
>     ....
> 
> if __name__ == '__main__':
>     somefunc(sys.argv)
> ====================
>     I hope you see my problem, I want to pass the values of sys.argv (or any 
> list for that matter) as arguments to somefunction, without resorting to 
> something like:
> ====================
> def somefunc(list)
>     arg1, arg2 = list[1], list[2] or someOtherValue
>     ....
>     ....
>     ....
> 
> if __name__ == '__main__':
>     somefunc(sys.argv)
> ====================
>
>     ....which I think is kinda ugly for more that 3 arg values (python
> sure does makes one *very* picky :))


I see!  Yes, you can do this by using apply().  Here's a toy example:

###
>>> def add(x, y=None):
...     if y == None: y = 0
...     return x + y
... 
>>> apply(add, [1, 2])
3
>>> apply(add, [1])
1
###

apply() is specifically designed for this kind of stuff, where the second
argument is a list that will be used for the arguments of a function.  You
can see more about apply() here:

    http://python.org/doc/current/lib/built-in-funcs.html

Python has an alterative way of doing this as of 2.0, by using starred
notation.  Take a look at:

    http://python.org/2.0/new-python.html#SECTION0001010000000000000000

for an explanation about it.


Good luck!