[Tutor] Difference between a class & module? (original) (raw)

Gregor Lingl glingl at aon.at
Fri Jul 2 15:24:23 EDT 2004

Derek Pienaar schrieb:

Halo Guys.

I need to clear up some confusion regarding a class and a module. This question came up when I saw an example in "a byte of python" tutorial, where the join method was used, but (as I saw it) without importing the string module (as I understood it). I thought that some frequently used "modules" were built-in and that string was one of them... not so. I understand what a class does ... among other things, it mainly defines or is a template for an object. I understand the concept of objects & instances but thought that a module was exactly the same as a class. To my surprise, I heard it not to be so. What then is a module? Please try and keep the explanation plain and simple if possible :-)

A module simply is a file, which contains Python statements. Normally among these there are def statements - so execution of the module defines some functions - and class statements - so execution of the module defines smo classes. A module may also contain names (variables) and other directly executable Python statements.

names (of functions, classes, variables) can be imported with the import statement:

import

or

from module import <name1, name2 ...>

In the latter case you can use the names directly, in the first one you have to qualify them with the module name via dot-notation

module.name

May be your confusion araouse becaue there was a heavily used module string which has become less often used since strings are built in objects in Python which have their own methods.

Old fashioned way:

import string s = string.upper(s)

Modern way:

no import necessary

s = s.upper()

Hope this helps. (Certainly additional explanations will follow ;-) )

Regards, Gregor

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