On 7/8/07, Walter Dörwald
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/)