Unpacking arguments: only named arguments may follow *expression

Question

The following works beautifully in Python:

def f(x,y,z): return [x,y,z]

a=[1,2]

f(3,*a)

The elements of a get unpacked as if

Answer 1

It doesn't have to be that way. It was just rule that Guido found to be sensible.

In Python 3, the rules for unpacking have been liberalized somewhat:

>>> a, *b, c = range(10)
>>> a
0
>>> b
[1, 2, 3, 4, 5, 6, 7, 8]
>>> c
9

Depending on whether Guido feels it would improve the language, that liberalization could also be extended to function arguments.

See the discussion on extended iterable unpacking for some thoughts on why Python 3 changed the rules.