changing the List's behaviour?

[Peter Otten]

meinrad recheis wrote:

> i want to change the List so that it returns None if the index for
> accesssing list elements
> is out of bound.

If you really need it, you can write a class similar to the one below:

class DefaultList(list):
    def __init__(self, sequence=[], default=None):
        list.__init__(self, sequence)
        self.default = default
    def __getitem__(self, index):
        try:
            return list.__getitem__(self, index)
        except IndexError:
            return self.default

if __name__ == "__main__":
    theList = DefaultList("abc", "?")
    print theList[1]
    print theList[99]

    theList = DefaultList(default="X")
    print theList[1]