On Tue, 06 Apr 2010 19:16:05 +0200, egbert wrote: > On Sun, Apr 04, 2010 at 12:10:02PM +0000, Steven D'Aprano wrote: > >> I can implement this tree using a flat dict: >> >> root = object() >> data = {root: ['Mammal', 'Reptile'], > > What is the advantage, or thougth behind, using an instance of object as > the root of your flat tree ? egbert
It's a known sentinel that can't possibly clash with an entry in the tree except by deliberate action on the part of the caller. I could have used None, or "root", or "this is a magic value that probably won't clash with an entry in the tree", or -1 as a sentinel instead, but they all risk accidental clashes with tree entries. -- Steven -- http://mail.python.org/mailman/listinfo/python-list