Newbie with some doubts.

[Claudio Grondi]

Mike Meyer wrote:
> Claudio Grondi <claudio.grondi at freenet.de> writes:
> 
>>Edgar A. Rodriguez wrote:
>>
>>>Hi everybody,
>>>Im newbie to Python (I found it three weeks ago) , in fact Im newbie
>>>to
>>>programming. I'm being reading and training with the language, but I
>>>still wondering about what Classes are used to. Could you please give
>>>me some examples??
> 
> 
> As far as I'm concerned, the definitive work in this area is Meyer's
> "Object Oriented Software Construction". He covers pretty much all the
> uses of OO language features, using a language that was designed
> specifically to support those uses. Be warned that after reading it,
> you're liable to come back to Python and wonder "Why doesn't Python do
> X".
> 
> For a good overview of a most programming paradigms, check out
> "Concepts, Techniques, and Models of Computer Programming" by Van Roy
> and Haridi. He covers OO programming, but not in as much depth as
> Meyer. But you'll see how it fits in with other paradigms.
> 
> 
>>There is actually no real need for usage of Classes.
> 
> 
> Well, there's actually no real need for usage of namespaces,
> functions, modules, and a host of other things one finds in modern
> programming languages, because all those languages are turing
> complete. But using those features makes it easier to write, read, and
> maintain programs - that's why the languages have them.
> 
> If your methods never use the self variable, or you never create more
> than one instance of a class, then there's a good chance your program
> would be easier to read if it didn't use classes. On the other hand,
> if you need multiple instances of some object, then an OO version of
> the program is often easier to read than the alternatives.
> 
> 
>>I for myself try to avoid classes where I can, especially
>>inheritance, because I consider the latter in most cases evil.
> 
> 
> Well, if you can do the job as well without classes or inheritance (or
> multiple inheritance, which some language designers dislike enough
> that they leave it out), then I'd say do it that way, because those
> are powerful mechanisms. More powerful mechanisms generally take more
> work to understand, so if a simpler mechanism - which should be easier
> to understand - can do the job, you should prefer it.
> 
> On the other hand, maintaining and extending the code is often part of
> the job. Using classes and inheritance make this part of the job much
> easier. For instance, I need to pickle builtin types that the provided
> pickle modules can't handle. If they hadn't used classes, or I chose
> not to use inheritance, I'd wind up working on that module - or a copy
> of it - and patching it to do what I want. Instead, I'm inheriting
> from the pickle modules classes, and extending them. This won't be a
> lot less work now. But when I upgrade my python installation, that
> changes. If I used "cut-n-paste" extension, my choices would be to use
> my version of the module, thus miss out on any bug fixes or
> enhancements that are in the new version of the module. Or I can try
> and port my patches into the new version, which could well be a lot of
> work. Since the pickle module uses classes and I inherited from them,
> upgrading Python means I automatically get any fixes and enhancements
> to that module. Since I'm only using the public interface, things
> should just simply work, with no effort on my part. They may not - so
> I need to rerun my tests. But I should do that after upgrading Python,
> even if I keep using the old module.
> 
>      <mike
Yes, I see your point, but even putting my personal preferences beside, 
for someone who just started to program, learning about the concept of 
classes and inheritance is probably not what helps to get immediate fun 
out of first steps in writing small programs, right?

Claudio