[Python-ideas] Boundaries for unpacking

[Stephen J. Turnbull]

Michel Desmoulin writes:

 > Yes and you can also do that for regular slicing on list. But you don't,
 > because you have regular slicing, which is cleaner, and easier to read
 > and remember.

It's clean because it's well-defined.  Slices on general iterables
don't have an OWTDI.  For example, "a = somelist[:]" is an idiom for
copying somelist to a so that destructive manipulations of a don't
change the original.  Should "a = someiterable[:]" reproduce those
semantics?  After "head, tail = someiterable" should tail contain a
list or someiterable itself or something else?

"WIBNI iterable[] worked" has already been posted to this thread about
5 times, and nobody disagrees that IWBN.  But slicing and unpacking of
iterables are fraught with such issues.  It's time the wishful
thinkers got down to edge cases and wrote a PEP.