Steve Jobless wrote: > Unfortunately, I don't see a way > to separate interface from implementation in Python. So, it may not make > much difference whether you subclass it or hack it from the outside.
Documentation. (And name-mangling, underscore prepending, all the stuff the others said.) Whenever I use a 3rd party library, I consult the docs to see how it works and which functions do what. The interface is what is published and the implementation is what you find if you dig around in the module. Yes, there's little in the way of run-time enforcement of this divide. But that's because Python gives you other benefits that come from run-time assignment and re-assignment of attributes. It's a common and powerful idiom that you find in several languages, especially that are wholly or partially prototype-based, such as Javascript. > Unfortunately, it seems to be taking unnecessary risk. I was > hoping someone shows me a compelling reason to sacrifice the safety, but > I don't hear much. I think the main issue is that tracking whether an attribute is public or private and whether an accessing scope is allowed to access it would impose a burden on the language developers, extra typing for users, and a run-time performance penalty, in the pursuit of some degree of 'safety' that isn't universally agreed to be useful. With this in mind, the name-mangling approach is a very reasonable middle ground. Every language has a philosophy and Python's differs from that of (for example) Java. It may not be suitable for large teams of mediocre programmers who require the compiler to keep them in line, but might produce better results than Java in other circumstances. -- Ben Sizer -- http://mail.python.org/mailman/listinfo/python-list
