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[Python-Dev] accumulator display syntax

Shane Holloway (IEEE) shane.holloway at ieee.org
Fri Oct 17 14:50:34 EDT 2003 
Armin Rigo wrote:

> Hello,
> 
> On Fri, Oct 17, 2003 at 11:55:53AM -0600, Shane Holloway (IEEE) wrote:
> 
>>    mygenerator = x for x in S
>>
>>    for y in x for x in S:
>>        print y
>>
>>    return x for x in S
> 
> 
> Interesting but potentially confusing: we could expect the last one to mean
> that we executing 'return' repeatedly, i.e. returning a value more than once,
> which is not what occurs.  Similarily,
> 
>    yield x for x in g()
> 
> in a generator would be quite close to the syntax discussed some time ago to
> yield all the values yielded by a sub-generator g, but in your proposal it
> wouldn't have that meaning: it would only yield a single object, which happens
> to be an iterator with the same elements as g().

Yes, this is one of the things I trying to getting at -- If gencomps are 
expressions, then they must be expressions everywhere, or my poor brain 
will explode.

As for the subgenerator "unrolling", I think there has to be something 
added to the yield statement to accomplish it -- because it is also 
useful to yield a generator itself and not have it unrolled.  My 
favorite was "yield *S" for that discussion...\

-Shane Holloway
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