Style question on recursive generators

Alex Martelli aleaxit at yahoo.com
Tue Oct 19 10:58:11 CEST 2004


Dima Dorfman <d+pylist at nospamplease.trit.org> wrote:

> Alex Martelli <aleaxit at yahoo.com> wrote:
> > If the issue is strictly one of whether it's worth somehow making
> >     for x in y: yield x
> > terser (by a new kw, combination of kw, and/or punctuation) I guess we
> > can discuss that (I just don't see the gain to offset the price of 
> > introducing new syntax and one more language thing to learn for 
> > Pythonistas and newcomers to Python).
> 
> I find myself writing a lot of recursive generators, and a while ago I
> implemented this:
> 
>   yield *other
> 
> to mean:
> 
>   for x in other:
>     yield x
> 
> No new keywords, and the asterisk is already used for a similar
> purpose (iterator expansion) in the function call syntax.
> 
> Thoughts? "Neat!" or "Yuck!"?

Looks to me roughly equivalent to such proposals as 'yield from other';
not totally out of whack but IMHO not warranted.  Re specifically
expanding the use of prefix *, I think there might be other good uses
for that -- say:
    a = b, *c, d
meaning the same as
    a = (b,) + tuple(c) + (d,)
or the old, currently out of favour proposal
    a, b, c, *d = e
where d gets (an iterator for) 'the rest of e' after the first three
items of e are unpacked to a, b, and c.  If your idea to specialcase the
* after a yield can work together with these other possibilities, the
whole package might perhaps get in together.


Alex



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