Static properties

Pete Shinners pete at shinners.org
Thu Aug 26 16:57:28 CEST 2004


Per Erik Stendahl wrote:
> Is it possible to define "static properties" in a class?

Variables defined at the class object level are what you consider 
"static" in C++. One thing that can trip people up is that these static 
attributes can be referenced from both the Class object and any Instance 
objects. But assignment to the static attribute can only happen on the 
Class object, otherwise the Instance will "shadow" the static attribute.

A simple class can demonstrate...

class Example(object):
     alpha = 1
     beta = 2
     def __init__(self):
         Example.cappa = Example.alpha + self.beta
         self.theta = 4

x = Example()
Example.alpha == x.alpha  #both are 1
x.beta = 42
Example.beta != x.beta    #now each have their own 'beta'
Example.theta             #AttributeError





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