Re: Generarl programming question.

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Date	Sun, 12 Apr 2015 01:15:06 +1000
Subject	Re: Generarl programming question.
From	Chris Angelico <rosuav@gmail.com>
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Show key headers only | View raw

On Sun, Apr 12, 2015 at 1:00 AM,  <jonas.thornvall@gmail.com> wrote:
> If two functions crossreference eachother back and forth what happen with the local variables.
>
> Will there be a new instance of function holding the variables or do they get messed up?

You mean if one function calls another, and that function calls the
first? That's called "mutual recursion":

def func1(x):
    if x % 2: return x + 1
    return func2(x - 2)

def func2(x):
    if x % 3: return x + 2
    return func1(x - 3)

The 'x' inside each function is completely separate, no matter how
many times they get called. They're usually stored on something called
a "call stack" - you put another sheet of paper on top of the stack
every time you call a function, local variables are all written on
that paper, and when you return from a function, you discard the top
sheet and see what's underneath.

For more information, search the web for the key terms in the above
description, particularly the ones I put in quotes.

If this isn't what you're talking about, the best way to clarify your
question is probably to post a simple (even stupidly trivial, like the
one above) example, and ask a question about that code. Someone'll
doubtless help out!

ChrisA

Thread

Generarl programming question. jonas.thornvall@gmail.com - 2015-04-11 08:00 -0700
  Re: Generarl programming question. Chris Angelico <rosuav@gmail.com> - 2015-04-12 01:15 +1000
    Re: Generarl programming question. jonas.thornvall@gmail.com - 2015-04-11 08:22 -0700
      Re: Generarl programming question. Chris Angelico <rosuav@gmail.com> - 2015-04-12 01:28 +1000
    Re: Generarl programming question. Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-04-11 18:23 +0200
      Re: Generarl programming question. Terry Reedy <tjreedy@udel.edu> - 2015-04-11 14:47 -0400
        Re: Generarl programming question. Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-04-11 21:19 +0200
          Re: Generarl programming question. Terry Reedy <tjreedy@udel.edu> - 2015-04-11 17:12 -0400
            Re: Generarl programming question. Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-04-12 00:05 +0200
              Re: Generarl programming question. Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-04-12 15:04 +1000
  Re: Generarl programming question. Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-04-12 01:25 +1000
    Re: Generarl programming question. jonas.thornvall@gmail.com - 2015-04-11 08:36 -0700

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