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Groups > comp.lang.python > #99792

Re: static variables

From Ulli Horlacher <framstag@rus.uni-stuttgart.de>
Newsgroups comp.lang.python
Subject Re: static variables
Date 2015-12-01 11:47 +0000
Organization University of Stuttgart, FRG
Message-ID <n3k1df$scd$1@news2.informatik.uni-stuttgart.de> (permalink)
References <n3i06o$9ot$1@news2.informatik.uni-stuttgart.de> <n3ibkd$nl0$1@dont-email.me> <565cf163$0$1612$c3e8da3$5496439d@news.astraweb.com> <n3jljn$os2$1@news2.informatik.uni-stuttgart.de> <mailman.60.1448963939.14615.python-list@python.org>

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Wolfgang Maier <wolfgang.maier@biologie.uni-freiburg.de> wrote:

> I'm wondering whether you have a good reason to stick with a function. 

Easy handling, no programming overhead. Clean, orthogonal code.


> What you are trying to achieve seems to be easier and cleaner to 
> implement as a class:
> 
> class Counter (object):
>     def __init__ (self, start_value=0):
>         self.x = start_value
> 
>     def __call__ (self):
>         self.x += 1
> 
> 1) solves the renaming problem
> 2) allows you to have several counters around:
> 
> counter1 = Counter()
> counter2 = Counter()
> counter3 = Counter(35)
> counter1()
> counter2()
> counter1()
> print (counter1.x, counter2.x, counter3.x)

Implementing a counter was only an example for a static variable, not the
primary goal.

With a class, I find it irritating the first function call have to be
different than the subsequent ones:


def main():
  a=A(1)
  a(1)
  a(5)
  a(0)
  print(a.n)

class A(object):
  def __init__ (self,*arg):
    self.n = 0

  def __call__(self,x):
    self.n += 1
    print('%d:' % self.n,x)

main()



-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher@tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/

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Thread

static variables Ulli Horlacher <framstag@rus.uni-stuttgart.de> - 2015-11-30 17:15 +0000
  Re: static variables Terry Reedy <tjreedy@udel.edu> - 2015-11-30 12:38 -0500
  Re: static variables BartC <bc@freeuk.com> - 2015-11-30 20:32 +0000
    Re: static variables Steven D'Aprano <steve@pearwood.info> - 2015-12-01 12:01 +1100
      Re: static variables Ulli Horlacher <framstag@rus.uni-stuttgart.de> - 2015-12-01 08:26 +0000
        Re: static variables Peter Otten <__peter__@web.de> - 2015-12-01 10:01 +0100
        Re: static variables Grobu <snailcoder@retrosite.invalid> - 2015-12-01 10:15 +0100
          Re: static variables Steven D'Aprano <steve@pearwood.info> - 2015-12-02 12:02 +1100
            Re: static variables Erik <python@lucidity.plus.com> - 2015-12-02 01:16 +0000
              Re: static variables Steven D'Aprano <steve@pearwood.info> - 2015-12-02 12:24 +1100
                Re: static variables Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-12-02 09:21 +0100
                Re: static variables Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-12-02 09:34 +0100
                Re: static variables Steven D'Aprano <steve@pearwood.info> - 2015-12-02 21:22 +1100
                Re: static variables Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-12-02 12:09 +0100
                Re: static variables Steven D'Aprano <steve@pearwood.info> - 2015-12-03 00:11 +1100
                Re: static variables Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-12-02 14:41 +0100
                Re: static variables Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-12-02 13:48 +0000
                Re: static variables Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-12-02 15:07 +0100
                Re: static variables Ian Kelly <ian.g.kelly@gmail.com> - 2015-12-02 08:15 -0600
                Re: static variables Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-12-02 14:31 +0000
                Re: static variables Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-12-02 16:30 +0100
                Re: static variables Ian Kelly <ian.g.kelly@gmail.com> - 2015-12-02 14:30 -0600
                Re: static variables Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-12-03 10:06 +0100
                Re: static variables Chris Angelico <rosuav@gmail.com> - 2015-12-02 20:23 +1100
                Re: static variables Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-12-02 10:47 +0100
                Re: static variables Marko Rauhamaa <marko@pacujo.net> - 2015-12-02 12:18 +0200
                Re: static variables Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-12-02 11:56 +0100
                Re: static variables Marko Rauhamaa <marko@pacujo.net> - 2015-12-02 13:30 +0200
                Re: static variables Steven D'Aprano <steve@pearwood.info> - 2015-12-03 00:17 +1100
        Re: static variables Wolfgang Maier <wolfgang.maier@biologie.uni-freiburg.de> - 2015-12-01 10:58 +0100
          Re: static variables Ulli Horlacher <framstag@rus.uni-stuttgart.de> - 2015-12-01 11:47 +0000

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