static variables

[Ulli Horlacher]

Wolfgang Maier <wolfgang.maier at 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 at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
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70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/