Example use:
def f(a, b, c, d):
print(a, b, c, d, sep = '&')
f(1,2,3,4)
>>> 1&2&3&4
f(*[1, 2, 3, 4])
>>> 1&2&3&4
Where in the python documentation is *
explained?
The *args
calling convention is documented in the Expressions reference:
If the syntax
*expression
appears in the function call,expression
must evaluate to an iterable. Elements from this iterable are treated as if they were additional positional arguments; if there are positional arguments x1, ..., xN, andexpression
evaluates to a sequence y1, ..., yM, this is equivalent to a call with M+N positional arguments x1, ..., xN, y1, ..., yM.
So, since you used [1, 2, 3, 4]
as the expression, which is an iterable, and there were no other positional arguments, it is treated as a call with M=0 and N=4, for a total of 4 positional arguments.
You can thus also call your function as f(1, 2, *[3, 4])
or any other combination of iterable and positional arguments, provided the iterable comes after the positionals.