cool .. thanks everyone. here is the aforementioned faq. http://www.python.org/doc/faq/general/#why-are-default-values-shared-between-objects
On Apr 17, 5:16 am, Arnaud Delobelle <[EMAIL PROTECTED]> wrote: > matthewperpick wrote: > > Check out this toy example that demonstrates some "strange" behaviour > > with keyword arguments and inheritance. > > > ================================= > > > class Parent: > > def __init__(self, ary = []): > > self.ary = ary > > [snip] > > As pointed out earlier, default values for arguments are evaluated > when the function is defined, not when it is called. This creates > confusion if this value is mutable and later mutated; I got confused > by it when I started python. So it is often not a good idea to use > mutable objects as default arguments. > > A simple fix: > > def __init__(self, ary=None): > if ary is None: ary = [] > self.ary = ary > > -- > Arnaud -- http://mail.python.org/mailman/listinfo/python-list
