On 7/8/07, Walter Dörwald <[EMAIL PROTECTED]> wrote: [quoting Guido] > > But I still want to hear of a practical use case for the default here. > > In most cases > > foo = getitem(iterable, 0, None) > if foo is not None: > ... > > is simpler than: > > try: > foo = getitem(iterable, 0) > except IndexError: > pass > else: > ... > > Here is a use case from one of my "import XML into the database" scripts: > > compid = getitem(root[ns.Company_company_id], 0, None) > if compid: > compid = int(compid) > > The expression root[ns.company_id] returns an iterator that produces all > children of the root node that are of the element type company_id. If > there is a company_id its content will be turned into an int, if not > None will be used.
Ahem. I hope you have a better use case for getitem() than that (regardless of the default issue). I find it clearer to write that as try: compid = root[ns.company_id].next() except StopIteration: compid = None else: compid = int(compid) While this is more lines, it doesn't require one to know about getitem() on an iterator. This is the same reason why setdefault() was a mistake -- it's too obscure to invent a compact spelling for it since the compact spelling has to be learned or looked up. -- --Guido van Rossum (home page: http://www.python.org/~guido/) _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
