python - passing a tuple in *args

Question

I'd like to pass a tuple (or maybe a list) to a function as a sequence of values (arguments). The tuple should be then unpacked as an argument into *arg.

For example, this is clear:

def func(*args):
    for i in args:
        print "i = ", i

func('a', 'b', 3, 'something')

But what I want to do is this:

tup = ('a1', 'a2', 4, 'something-else')
func(tup)

And this should behave similar to the first case. I think I should use here reprint and eval but not sure how exactly.

I know that I can just pass the tuple in the function and then unpack it within the body, but my question here is how to unpack it in the function call itself.

Answer 1

You can just use func(*tup) to unpack the tuple directly when you invoke the function.

>>> func(*tup)
i =  a1
i =  a2
i =  4
i =  something-else

This is kind of equivalent to func(tup[0], tup[1], tup[2], ...). The same also works if the function expects multiple individual parameters:

>>> def func2(a, b, c, d):
...     print(a, b, c, d)
...
>>> func2(*tup)
('a1', 'a2', 4, 'something-else')

See e.g. here for more in-depth background on the syntax.