[Tutor] Difference between a class & module?

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 <module>


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


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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