SuperZE wrote: >> Because you declare myList to be a *class*-level variable, which means >> *all* instances of that class (a and b in your case) *share* it. Python >> does not declare *instance* variables the way you do. >> >> Instead, do this: >> >> class Foo(object): >> def __init__(self): >> self.myList = [] > > > Interesting, but that does not explain the difference in the behavior > of myList and myInt
Sorry, I forgot that. The reason is simple - lists are mutable. Numbers aren't. And when you *assign* to an instance a value, it will be set on the instance, not on the class. The same happens (as you've already seen for yourself) when you do a.myList = [] as this creates a new list, stored only on a. > Both were class-level variables, as far as I can see, and therefor a > and b should also share it Nope. To change it, you need to do Test1.myInt = 5 The thing is that the lookup triggered by getattr/dotted notation goes roughly like this: 1) try to find the attribute (value *or* method! Python doesn't distinguish) in the instance itself. 2) if not found there, look at the class. 3) if not found there, look at the base-classes in the method resolution order (MRO) There are some other things involved - descriptor protocol calls on the class-level lookups - but that's not relevant for the problem at hand. OTOH, when setting with setattr/dotted notation, it will always set on the object passed. Diez -- http://mail.python.org/mailman/listinfo/python-list
