Bruno Desthuilliers wrote: > hdixon a écrit : > > Ive spent a few days going thru a couple of Python tutorials. No > > problem until I got to classes. I guess my java mindset is blocking my > > vision. > > Then http://dirtsimple.org/2004/12/python-is-not-java.html > > > I've borrowed another thread's code snippet and cannot explain > > the results: > > class MyClass: > > class MyClass(object): > > > list = [] > > This may not be too harmful in the given context, nut shadowing builtin > types may not be a good idea. > > > myvar = 10 > > > > def add(self, x): > > self.list.append(x) > > "list" is a class attribute. It's shared by all instances of MyClass. > This is a FAQ AFAICT. > > > self.myvar = x > > This creates an instance attribute named myvar that shadows the class > attribute of the same name > > (snip expected results) > > > WHY do the "class members" list and myvar seem to behave differently? > > cf above. And notice that in Python, binding (aka 'assignement') and > name lookup on objects are different beasts. There have been quite a few > threads about this recently. > > > Given the way that list[] is supposedly shared why doesnt myvar exhibit > > the same behavior? > > Because binding to self.myvar creates the instance attribute "myvar". > Notice that you have not rebound "list". > > > It seems that myvar is acting like a true "instance > > member". > > It is one. > > > Is this simply because of the underlying types? > > Nope, it's because in the first case (MyClass.list, accessed as > self.list) you just call methods on the list object, which has no effect > on the binding.
ok - i "think" its beginning to dawn on me. BTW - the blog above was a good read for me. I _am_ trying to bring java into the mix and its screwing me up big time. I'll go back over the chapters that dicuss binding/name lookups. Thanks -- http://mail.python.org/mailman/listinfo/python-list
