You have been bitten by a well known "feature". You used a mutable as default value in your argument list for __init__.
See: http://www.nexedi.org/sections/education/python/tips_and_tricks/python_and_mutable_n/view It would be better to write: class structure: def __init__(self, folders = None): self.folders=folders or [] -Larry Bates keithlackey wrote: > I'm relatively new to python and I've run into this problem. > > > DECLARING CLASS > > class structure: > def __init__(self, folders = []): > self.folders = folders > > def add_folder(self, folder): > self.folders.append(tuple(folder)) > > > > Now I try to make an instance of this class > > structure1 = structure() > structure1.add_folder([('foo'),]) > print structure1.folders > > This returns: [('foo',)] > > This works fine. But when I try to make another instance of that class... > > structure2 = structure() > print structure2.folders > > This now also returns: [('foo',)] > Even though I haven't added any folders to this new instance > > What am I doing wrong? > -- http://mail.python.org/mailman/listinfo/python-list
