[Python-Dev] problem with genexp

[Jiwon Seo]

Regarding this Grammar change;  (last October)
     from   argument: [test '=' ] test [gen_for]
     to      argument: test [gen_for] | test '=' test ['(' gen_for ')']

- to raise error for "bar(a = i for i in range(10)) )"

I think we should change it to
     argument: test [gen_for] | test '=' test

instead of
     argument: test [gen_for] | test '=' test ['(' gen_for ')']

that is, without ['(' gen_for ')'] . We don't need that extra term,
because "test" itself includes generator expressions - with all those
parensises.
Actually with that extra ['(' gen_for ')'] ,   foo(a= 10 (for y in
'a')) is grammartically correct ; although that error seems to be
checked elsewhere.

I tested without ['(' gen_for ')'] , and worked fine passing
Lib/test/test_genexps.py

-Jiwon

On 10/20/05, Neal Norwitz <nnorwitz at gmail.com> wrote:
> On 10/16/05, Neal Norwitz <nnorwitz at gmail.com> wrote:
> > On 10/10/05, Neal Norwitz <nnorwitz at gmail.com> wrote:
> > > There's a problem with genexp's that I think really needs to get
> > > fixed.  See http://python.org/sf/1167751 the details are below.  This
> > > code:
> > >
> > > >>> foo(a = i for i in range(10))
> > >
> > > I agree with the bug report that the code should either raise a
> > > SyntaxError or do the right thing.
> >
> > The change to Grammar/Grammar below seems to fix the problem and all
> > the tests pass.  Can anyone comment on whether this fix is
> > correct/appropriate?  Is there a better way to fix the problem?
>
> Since no one responded other than Jiwon, I checked in this change.  I
> did *not* backport it since what was syntactically correct in 2.4.2
> would raise an error in 2.4.3.  I'm not sure which is worse.  I'll
> leave it up to Anthony whether this should be backported.
>
> BTW, the change was the same regardless of old code vs. new AST code.
>
> n
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