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Re: recursive function: use a global or pass a parameter?

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Tim wrote:
> I have this type of situation and wonder if I should use a global variable
> outside the recursive function instead of passing the updated parameter
> through.

No! Globals are evil, at least for that sort of thing.
The way you're doing it is fine.

The only thing I would change is to wrap it all up
in a top-level function that takes care of creating
the result set and returning it.

def walk(obj):
   res = set()
   _walk(obj, res)
   return res

def _walk(obj, res):
   ...

-- 
Greg

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Thread

recursive function: use a global or pass a parameter? Tim <jtim.arnold@gmail.com> - 2015-01-16 09:49 -0800
  Re: recursive function: use a global or pass a parameter? Chris Angelico <rosuav@gmail.com> - 2015-01-17 04:56 +1100
    Re: recursive function: use a global or pass a parameter? Rustom Mody <rustompmody@gmail.com> - 2015-01-16 10:22 -0800
  Re: recursive function: use a global or pass a parameter? Peter Otten <__peter__@web.de> - 2015-01-16 19:34 +0100
    Re: recursive function: use a global or pass a parameter? Tim <jtim.arnold@gmail.com> - 2015-01-16 10:48 -0800
    Re: recursive function: use a global or pass a parameter? Yawar Amin <yawar.amin@gmail.com> - 2015-01-16 18:23 -0800
      Re: recursive function: use a global or pass a parameter? Yawar Amin <yawar.amin@gmail.com> - 2015-01-16 21:29 -0800
      Re: recursive function: use a global or pass a parameter? Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-01-18 10:25 +1300
  Re: recursive function: use a global or pass a parameter? Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-01-17 11:20 +1300
    Re: recursive function: use a global or pass a parameter? Chris Angelico <rosuav@gmail.com> - 2015-01-17 10:49 +1100
  Re: recursive function: use a global or pass a parameter? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-17 21:15 +1100
    Re: recursive function: use a global or pass a parameter? Roy Smith <roy@panix.com> - 2015-01-17 10:20 -0500
      Re: recursive function: use a global or pass a parameter? Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-01-18 10:07 +1300
  Re: recursive function: use a global or pass a parameter? albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-01-17 17:30 +0000
    Re: recursive function: use a global or pass a parameter? Chris Angelico <rosuav@gmail.com> - 2015-01-18 06:27 +1100

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