Re: Unclear On Class Variables

[Steve Holden]

Tim Daneliuk wrote:
I am a bit confused.  I was under the impression that:
class foo(object):
    x = 0
    y = 1
means that x and y are variables shared by all instances of a class.
What it actually does is define names with the given values *in the 
class namespace*.

But when I run this against two instances of foo, and set the values
of x and y, they are indeed unique to the *instance* rather than the
class.
I imagine here you are setting instance variables, which then *mask* the 
presence of class variables with the same name, because "self-relative" 
name resolution looks in the instance namespace before it looks in the 
class namespace.

It is late and I am probably missing the obvious.  Enlightenment 
appreciated ...
You can refer to class variables using the class name explicitly, both 
within methods and externally:

 >>> class X:
 ...   count = 0
 ...   def getCt(self):
 ...     return self.count
 ...   def inc(self):
 ...     self.count += 1
 ...
 >>> x1 = X()
 >>> x2 = X()
 >>> id(x1.count)
168378284
 >>> x1.inc()
 >>> id(x1.count)
168378272
 >>> id(x2.count)
168378284
 >>> id(X.count)
168378284
 >>> x1.getCt()
1
 >>> x2.getCt()
0
 >>>
regards
 Steve
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