On Mar 12, 4:51 pm, Alan Isaac <[EMAIL PROTECTED]> wrote: > I was surprised to see that > comparison is slated for death > in Python 3000. > > For example:http://www.python.org/dev/peps/pep-3100/ > list.sort() and builtin.sorted() methods: eliminate cmp parameter > [27] [done]
Hmm, wasn't aware they were taking it that far. You should almost always avoid using the cmp parameter because it's very inefficient; instead, look at the key parameter which is a function that maps objects in a your sequence to a sort key and sorts on that. So instead of (for a simple example): s.sort(cmp=lambda a,b: cmp(a.get_id(),b.get_id())) You would use: s.sort(key=lambda a:a.get_id()) (However, there are rare cases where you can't easily map your items to a sortable builtin. I suppose in those cases you'll have to use a custom comparison proxy. But I digress.) > But there is a rumor of a PEP to restore > comparisons.http://mail.python.org/pipermail/python-3000/2008-January/011764.html > > Is that going anywhere? No. > Also, what is the core motivation for removing this functionality? The basically replaced it with a better one. Instead of the cmp methods above, use the key method. Instead of __cmp__ method for overriding object operators, use the rich comparison methods: __lt__, __gt__, and so on. Python 2.x currently implements both cmp and rich comparisons at the same time, but that creates a lot of underlying complexity, so they got rid of it. Carl Banks -- http://mail.python.org/mailman/listinfo/python-list
