将元组扩展为参数

Is there a way to expand a Python tuple into a function – as actual parameters?

For example, here expand() does the magic:

some_tuple = (1, "foo", "bar")

def myfun(number, str1, str2):
    return (number * 2, str1 + str2, str2 + str1)

myfun(expand(some_tuple)) # (2, "foobar", "barfoo")

I know one could define myfun as myfun((a, b, c)), but of course there may be legacy code. Thanks

myfun(*some_tuple) does exactly what you request. The * operator simply unpacks the tuple (or any iterable) and passes them as the positional arguments to the function. Read more about unpacking arguments.

Note that you can also expand part of argument list:

myfun(1, *("foo", "bar"))

Take a look at the Python tutorial section 4.7.3 and 4.7.4. It talks about passing tuples as arguments.

I would also consider using named parameters (and passing a dictionary) instead of using a tuple and passing a sequence. I find the use of positional arguments to be a bad practice when the positions are not intuitive or there are multiple parameters.

This is the functional programming method. It lifts the tuple expansion feature out of syntax sugar:

apply_tuple = lambda f, t: f(*t)

Example usage:

from toolz import * 
from operator import add, eq

apply_tuple = curry(apply_tuple)

thread_last(
    [(1,2), (3,4)],
    (map, apply_tuple(add)),
    list,
    (eq, [3, 7])
)
# Prints 'True'

curry redefiniton of apply_tuple saves a lot of partial calls in the long run.