classes and list as parameter, whats wrong?

[Dirk Zimmermann]

Hi!

I have a problem in a program. And I don't understand what is going on.
I can code something, that the "error" doesn't occur anymore. But I
still don't know the reason and this is unsatisfactory: Did I understood
something wrong or is there a bug? To make it short, I boiled down the
program to the crucial part.  It looks like this:

----------- START ------------
#!/usr/bin/env python

class cClass:
    """ Base class to handle playlists, i.e. the files, the name, etc. """
    def __init__(self, LL=[]):
        self.list=LL
    def addFile(self,L):
        self.list.append(L)

def main():
    l1 = ['a','b','c']
    lNames=['n1','n2','n3']
    for name in lNames:
        objC=cClass()
        for each in l1:
            objC.addFile(each)
        print objC.list
        del objC

if __name__ == "__main__":
    main()
----------- END ----------------

If I start it, I get the following output:

['a', 'b', 'c']
['a', 'b', 'c', 'a', 'b', 'c']
['a', 'b', 'c', 'a', 'b', 'c', 'a', 'b', 'c']


Why does this list grow? I thought, with every new instance the list LL
is set to []?

How can bring light in this?


Best,
    Dirk