Multiple instances of modules

[Peter Otten]

Daniel Pryde wrote:

> Hi there.
> 
> I'm currently trying to learn Python, my aim being to create my final
> year project at university using only Python instead of Java. I've run
> into a problem though while trying to make multiple instances of
> modules.
> 
> For example, say I made a CD.py module which held details of an audio
> compact dic (album name, track names, etc..), and wanted my Python
> script to make a record collection using multiple CD's, I can't make
> them seperately. I tried using the 'import module as name' format, but
> any changes made to one instance affects the other. I assume this is
> because Python is simply referencing the one instance of CD.py rather
> than seperate ones. Is there a solution to this that doesn't involve
> using cPython or Jython? Any help would be greatly appreciated.

There is no connection between a class name and a module name enforced by
the language. If you already know a programming language, I strongly
recommend the tutorial that comes with the python distribution.

Below is a minimalist CD class with an example usage to get you started. 
(In Python you say CD() instead of Java's new CD())

#module cd.py
class CD:
    def __init__(self, composer, title):
        self.composer = composer
        self.title = title
    def __str__(self):
        return "%s: %s" % (self.composer, self.title)
#end module cd.py

#module main.py
from cd import CD
cdcoll = []
cdcoll.append(CD("Orff", "Carmina Burana"))
cdcoll.append(CD("Bach", "Goldberg-Variationen"))

for disk in cdcoll:
    print disk
#end module main.py     

Peter