[Python-Dev] accumulator display syntax
Armin Rigo
arigo at tunes.org
Fri Oct 17 14:28:11 EDT 2003
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().
Even with parenthesis, and assuming a syntax to yield from a sub-generator for
performance reason, the two syntaxes would be dangerously close:
yield x for x in g() # means for x in g(): yield x
yield (x for x in g()) # means yield g()
Armin
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