En Sun, 20 May 2007 17:27:20 -0300, Arnaud Delobelle <[EMAIL PROTECTED]> escribió:
> Hi all, > > I often find myself needing to get (non-destructively) the value of > the member of a singleton set. Is there a good way to do this (as an > expression?) None of the ones I can think of satisfy me, eg: > > * list(myset)[0] > * iter(myset).next() > * set(myset).pop() > > What I would like is something like a 'peek()' function or method > (would return the same as pop() but wouldn't pop anything). I would > like to know of a better idiom if it exists. If not, isn't there a > need for one? Yes, something like peek() or any() would be useful. But you're not restricted by the builtin methods, you could write your own: def peek(iterable): return iter(iterable).next() maybe converting the possible StopIteration into another exception like EmptyContainer(ValueError). > Note: it is comparatively easier to do this destructively: > myset.pop() > or to bind a name to the member: > element, = myset If you know that your set contains exactly one element, I like the later form. > PS: this problem is not restricted to sets but could occur with many > 'container' types. Yes, and I've seen all your expressions, plus some more, like: for x in container: break All of them are rather ugly... -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
