Positional and Keyword Arguments (Livehacking Screenplay)

Plain Function with Positional Arguments

code/10-plain-positional.py
def f(a, b):
    print(a, b)

f(1, 2)
f(a=3, b=4)

$ python code/10-plain-positional.py
1 2
3 4

Arbitrary Number of Arguments?

code/20-arbitrary-positional-tuple.py
def f(*args):
    print(args)

f(1, 2, 3)

$ python code/20-arbitrary-positional-tuple.py
(1, 2, 3)

  • A-ha: positional arguments passed as tuple

  • “Unpack” tuple as positional arguments?
code/30-unpack-positional.py
def f(*args):
    print(*args)

f(1, 2, 3)

$ python code/30-unpack-positional.py
1 2 3

  • Unpack any sequence as positional arguments?

$ python code/40-unpack-any-sequence-positional.py
1 2 3

And Keyword Arguments?

  • *args ⟶ no parameter names

  • no keyword arguments

code/50-keyword-dict.py
def f(**kwargs):
    print(kwargs)

f(a=1, b=2)

$ python code/50-keyword-dict.py
{'a': 1, 'b': 2}

  • A-ha: similar to *args, **kwargs is passed as dictionary

  • And unpacking ⟶ same: **