Python recursion with list returns None

Posted by newman on Stack Overflow See other posts from Stack Overflow or by newman
Published on 2010-04-08T10:41:09Z Indexed on 2010/04/08 10:43 UTC
Read the original article Hit count: 219

Filed under:

python

|

recursion

|

list

def foo(a):
    a.append(1)
    if len(a) > 10:
        print a
        return a
    else:
        foo(a)

Why this recursive function returns None (see transcript below)? I can't quite understand what I am doing wrong.

In [263]: x = []

In [264]: y = foo(x)
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]

In [265]: print y
None

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