Unclear On Class Variables

Peter Hansen peter at engcorp.com
Thu Jan 13 08:56:10 EST 2005

Simon Brunning wrote:
> On 13 Jan 2005 07:18:26 EST, Tim Daneliuk <tundra at tundraware.com> wrote:
> But you are being mislead by the fact that integers are immutable.
> 'spam.eggs = 2' is *creating* an instance member - there wasn't one
> before. Have a look at what happens with a mutable object:

Simon, it's really not about mutability at all.  You've changed
the example, which was binding a name (specifically setting an
attribute), to one in which you are simply calling a method on
the object.  If you change your example to bind the name the
same way, even with a mutable, it will work the same way as Tim's
original did with integers:

>>> class Spam(object):
... 	eggs = [3]
>>> spam = Spam()
>>> spam2 = Spam()
>>> spam.eggs = [7]
 >>> spam2.eggs


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