Francisco Couzo writes: > I'd be interested in writing a patch to make itertools more consistent if > there's a consensus.
I don't understand what you mean by "consistent". I would argue that in Python, an argument of None means "use the TOOWTDI default". For "filterfalse", bool() is pretty obvious for the default predicate since most Python classes do have a boolean interpretation. For "groupby", I guess the identity is the "intuitive" default. But for dropwhile, bool() or the identity seem like obvious choices, but intuitively they're not very useful since the head of what's left is a false-y. When would you want that? Typically false-ies are "nothing to see here, people, move along" values. I guess that consideration suggest lambda x: not(x), but I don't see why one would want to spell that dropwhile(None, ...) rather than dropwhile(not, ...), especially since in many contexts what you might really want (and expect None to default to) is dropwhile(lambda x: x is None, ...). Bottom line for me is that this use (and non-use) of None is consistent with Python practice regarding defaults. So, "accepts None" vs "doesn't accept None" doesn't seem to me to be an important enough consistency to impose unobvious semantics on dropwhile(None, ...). _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
