GMane Python wrote: > So, I forgot the last part of my example that might gel in your mind why > Objects are useful in certain situations. Ok so you maybe followed my > example of the shopping cart. Let's just forget for a moment the use for > shopping carts is for websites. Let's just say you were going to write the > lines directly into Python, like maybe at the IDLE interpreter. Like maybe > you're testing the functionality of the routine for correctness, not actual > implementation. > > [good introductory class stuff snipped] > > > In a class, you can have a variable 'total' and you can have a variable > 'self.total'. The first is just accessible from within the structure of the > class. The latter is accessible from outside the class. So, using a class > with the variable self.total, you can from outside the class say: > > > > print ShoppingCart["Dave"].total > > > > to get the value of the variable self.total. (That had me buggered for a > while ..... ) > Thanks for the smile this gave me. We all get to this stage periodically when programming. > > > If you can wrap your mind around this, you're well on your way to using OOP > I believe. If not, , don't give up. I'm just a python/programming newbie > and maybe missed the boat completely with my posting. > Well maybe you did, but you actually managed to demonstrate important parallels between namespaces and dictionaries in Python. > > > Another quite important part I didn't even mention was sub-classing. That's > taking a class, and 'inheriting' it's code to your class as a base, then you > can re-write or adddifferent methods. But, first I think it's important to > understand how to have several instances of a single class running in > memory, each with different values for the defined variables. I'll let > someone else talk about that. > As indeed they almost inevitably will :-)
regards Steve -- Steve Holden +1 703 861 4237 +1 800 494 3119 Holden Web LLC http://www.holdenweb.com/ Python Web Programming http://pydish.holdenweb.com/ -- http://mail.python.org/mailman/listinfo/python-list
