Meta: PEP discussion (was Re: PEP 255: Simple Generators)

Tim Peters tim.one at home.com
Thu Jun 28 06:12:41 CEST 2001


[Greg Ewing]
> To behave totally like Icon, it would be necessary
> that given
>
>   def f():
>     return 3 + g()
>
> where g is a generator, and f is called in an iteration
> context, then f would be a generator too.

Actually not!  "return" does not supply a generative context in Icon, so

    return 3 + g()

produces at most one result regardless of the context f() was called from
and regardless of whether g "wants to" generate more than one result.  The
rules in Icon get subtle when crossing expression boundaries.  You need

    suspend 3 + g()

here instead to make that particular point stick; but then that's like the
PEP 255 example

    def f():
        for x in g():
            yield 3 + x

and then f is indeed a generator.

> But then you would have turned Python into Icon. :-)

Well, except for the really *interesting* parts <wink>.

BTW, did you get your Windows install to work???  If so, what was the
problem?





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