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Classes & Instances

Tim Hochberg tim.hochberg at ieee.org
Wed Jan 2 14:26:03 EST 2002 
"Andrew Nguyen" <pythonnet at hotmail.com> wrote in message
news:40dbad98.0201021100.2731aecd at posting.google.com...
> We all know that you can't use classes without instances.
>
> Now, for the problem. How do I get a class, so that when an instance
> is made of it, the class records the instance's name to a list.
>
> e.g,
> class a:
>      pass
>
> f = a

I assume you means "f = a()" here. If so, you probably want something like:

>>> class A:
...  instances = []
...  def __init__(self, name):
...   self.instances.append(self)
...   self.name = name
...  def __repr__(self):
...   return '<instance %s>' % self.name # Name is only around so this
prints something legible
...
>>> f = A('spam')
>>> g = A('eggs')
>>> h = A('more spam')
>>> A.instances
[<instance spam>, <instance eggs>, <instance more spam>]

You don't have to make instances a part of the class A, but that's what I'd
do.

-tim




> ----
>
> how do I get f into a list. And remember, my goal is _flexability_ so:
>
> class a:
>      pass
>
> f = a
>
> foolist = ['f']
>
> Will NOT work for my goal, but, if let's say there is a function,
> 'TakeInstanceName()':
>
> class a:
>      foolist[:-1]=TakeInstanceName()#This function takes the Instance
> name      #  whenever the class is refered to
>
> f = a
>
> #Now after that, foolist should have ['f'], but, my question is, what
> IS the #function that would take the TakeInstanceName()'s place?
> -----
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