On Thu, 31 Jul 2008 13:32:39 +0200, Thomas Troeger wrote: >> Can someone explain to me the difference between a type and a class? > > If your confusion is of a more general nature I suggest reading the > introduction of `Design Patterns' (ISBN-10: 0201633612), under > `Specifying Object Interfaces'. > > In short: A type denotes a certain interface, i.e. a set of signatures, > whereas a class tells us how an object is implemented (like a > blueprint). A class can have many types if it implements all their > interfaces, and different classes can have the same type if they share a > common interface.
I fear you're introducing a rather complicated answer for a simple question. In Python, the simple answer is that built-in objects like int, float, str etc. are referred to as "types", and custom objects created using the class keyword are referred to as "classes". This is a historical distinction that will disappear in time. We can see that types and classes already have the same type in Python: >>> class Parrot(object): ... pass ... >>> type(Parrot) <type 'type'> >>> type(str) <type 'type'> > The following example should clarify matters: > > class A: > def bar(self): > print "A" Alas, you've chosen the worst-possible example to "clarify" matters, because old-style classic classes are *not* unified with types, and will disappear in the future: >>> class Old: # don't inherit from object ... pass ... >>> type(Old) <type 'classobj'> So, to the Original Poster: In Python, new-style classes and types are the same, but it is traditional to refer to customer objects as "class" and built-in objects as "types". Old-style classes are different, but you are discouraged from using old-style classes unless you have a specific reason for needing them (e.g. backwards compatibility). -- Steven -- http://mail.python.org/mailman/listinfo/python-list
