user80112 user80112 -4 years ago 175
Python Question

Passing all elements of tuple in function 1 (from *args) into function 2 (as *args) in python

I am writing a function to take *args inputs, assess the data, then pass all inputs to the next appropriate function (align), also taking *args

*args seems to be a tuple. I have tried various ways of passing each element of the tuple into the next function, the latest two being:

for x in args:


for x in args:

Answer Source

You "unpack them" with *args. Then the receiving function can mop them up into a tuple again (or not!).

These examples should enlighten things:

>>> def foo(*f_args):
...     print('foo', type(f_args), len(f_args), f_args)
...     bar(*f_args)
>>> def bar(*b_args):
...     print('bar', type(b_args), len(b_args), b_args)
>>> foo('a', 'b', 'c')
('foo', <type 'tuple'>, 3, ('a', 'b', 'c'))
('bar', <type 'tuple'>, 3, ('a', 'b', 'c'))

Now, let's redefine bar and break the argspec:

>>> def bar(arg1, arg2, arg3):
...     print('bar redefined', arg1, arg2, arg3)
>>> foo('a', 'b', 'c')
('foo', <type 'tuple'>, 3, ('a', 'b', 'c'))
('bar redefined', 'a', 'b', 'c')
>>> foo('a', 'b')
('foo', <type 'tuple'>, 2, ('a', 'b'))
---> TypeError: bar() takes exactly 3 arguments (2 given)
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