How can i define a shared list in the recursive function in python?

Question

I want to encapsulate my function and define the list in the function, not before it: for example in this code:

s = []
def rec(n):
    if n == 0:
        return s
    else:
        s.append(n)
        rec(n-1)
        return s
print(rec(5))

but when i define it in the recursive function, it become local.

Answer 1

You can do this by pass the list (with a default value) in your recursive function's argument:

def rec(n, s=[]):
    if n == 0:
        return s
    else:
        s.append(n)
        rec(n-1, s)
        return s
print(rec(5))