Understanding how is a function evaluated using recursion

Newsgroups	comp.lang.python
Date	2013-09-25 16:24 -0700
Message-ID	<231e5958-97c9-489c-9cfa-0f4451f6520c@googlegroups.com> (permalink)
Subject	Understanding how is a function evaluated using recursion
From	Arturo B <a7xrturodev@gmail.com>

Show all headers | View raw

Hi, I'm doing Python exercises and I need to write a function to flat nested lists
as this one: 

[[1,2,3],4,5,[6,[7,8]]]

To the result:

[1,2,3,4,5,6,7,8]

So I searched for example code and I found this one that uses recursion (that I don't understand):

def flatten(l):
    ret = []
    for i in l:
        if isinstance(i, list) or isinstance(i, tuple):
            ret.extend(flatten(i)) #How is flatten(i) evaluated?
        else:
            ret.append(i)
    return ret

So I know what recursion is, but I don't know how is 

                       flatten(i)
 
evaluated, what value does it returns?

Thank you

Back to comp.lang.python | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

Understanding how is a function evaluated using recursion Arturo B <a7xrturodev@gmail.com> - 2013-09-25 16:24 -0700
  Re: Understanding how is a function evaluated using recursion Josh English <Joshua.R.English@gmail.com> - 2013-09-25 16:59 -0700
  Re: Understanding how is a function evaluated using recursion MRAB <python@mrabarnett.plus.com> - 2013-09-26 01:07 +0100
  Re: Understanding how is a function evaluated using recursion Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-09-26 00:10 +0000
  Re: Understanding how is a function evaluated using recursion Dave Angel <davea@davea.name> - 2013-09-26 00:26 +0000
  Re: Understanding how is a function evaluated using recursion Terry Reedy <tjreedy@udel.edu> - 2013-09-25 21:12 -0400
  Re: Understanding how is a function evaluated using recursion rusi <rustompmody@gmail.com> - 2013-09-25 21:04 -0700
  Re: Understanding how is a function evaluated using recursion Neil Cerutti <neilc@norwich.edu> - 2013-09-26 14:18 +0000
    Re: Understanding how is a function evaluated using recursion Neil Cerutti <neilc@norwich.edu> - 2013-09-26 14:23 +0000
      Re: Understanding how is a function evaluated using recursion Peter Cacioppi <peter.cacioppi@gmail.com> - 2013-09-28 13:24 -0700
  Re: Understanding how is a function evaluated using recursion rusi <rustompmody@gmail.com> - 2013-09-29 20:41 -0700

csiph-web