[Python-Dev] PEP 479: Change StopIteration handling inside generators

[Chris Angelico]

On Thu, Nov 20, 2014 at 7:48 AM, MRAB <python at mrabarnett.plus.com> wrote:
> The PEP says """any generator that depends on an implicitly-raised
> StopIteration to terminate it will have to be rewritten to either catch
> that exception or use a for-loop"""
>
> Shouldn't that be "... explicitly-raised ...", because returning raises
> StopIteration implicitly? ("raise StopIteration" is explicit)

The point here is primarily about some other function (maybe a
next(iter), or maybe something else entirely) raising StopIteration.
(If it explicitly raises StopIteration right there in the generator,
it can be trivially converted into a return statement, anyway.) The
return statement is an explicit indication that the generator should
now return; permitting a StopIteration to bubble up through and out is
the implicit option; but the 'plicitness' isn't necessarily obvious.

ChrisA