On Nov 28, 2017 12:32 AM, "Steven D'Aprano" <steve@pearwood.info> wrote: On Tue, Nov 28, 2017 at 06:15:47PM +1300, Greg Ewing wrote:
Steven D'Aprano wrote:
How does "stop iterating here" equate to a wildcard?
The * means "I don't care what else the sequence has in it".
Because I don't care, there's no need to iterate any further.
I'll grant you that. But I don't see how that relates to being a wildcard. I'm not seeing the connection. I mean, you wouldn't interpret from module import * to mean "I don't care what's in the module, so don't bother importing anything" would you? So the concept of wildcard here seems to be the opposite to its use here: - in imports, it means "import everything the module offers"; - in extended iterable unpacking, it means "collect everything"; both of which (to me) seem related to the concept of a wildcard; but in this proposed syntax, we have x, y, * = iterable which means the opposite to "collect everything", instead meaning "collect nothing and stop". Anyway, given that * = is visually ambiguous with *= I don't think this syntax is feasible (even though * = is currently a syntax error, or at least it is in 3.5). If not already considered, what if the RHS had to be explicitly unpacked? Something like: a, b, c = *iterator Which would essentially be: a, b, c = (*iterator,) This enables lazy assignment by default but `*` can force complete expansion (and exact matching) of the RHS. It's a breaking change, but it does have a straightforward fix (simply wrap and unpack any relevant RHS). Thanks, -- C Anthony