[Python-projects] astng: generator ignored GeneratorExit

[Sylvain Thénault]

On Mon, May 12, 2008 at 12:23:31PM +0200, Maarten ter Huurne wrote:
> Hi,

Hey Maarteen,
 
> When I run pylint on the following program:
> ===
> print {}[str(0) + ''].a
> ===
> 
> I see this message:
> ===
> Exception exceptions.RuntimeError: 'generator ignored GeneratorExit' in 
> <generator object at 0x835096c> ignored
> ===
> 
> Versions used:
> ===
> pylint 0.14.0,
> astng 0.17.2, common 0.31.0
> Python 2.5.1 (r251:54863, Jan 10 2008, 18:01:57)
> ===
> 
> Python 2.5 is essential to trigger this issue, since GeneratorExit was 
> introduced in that release.
> 
> The problem seems to be that _infer_operator() uses an "except:" clause that 
> catches all exceptions and then yields YES. Since GeneratorExit is an 
> exception, this means the generator will yield another value after the 
> Python VM told it to stop, which is the reason the Python VM prints that 
> message.
> 
> There is a patch at the end of this mail.

great, thank you very much for tracking this.
 
> In general, it seems to be unsafe to have a "yield" in a "try" body and in a 
> following "except:" or "except Exception:" clause, unless GeneratorExit is 
> explicitly dealt with in an earlier "except" clause. Maybe this could 
> become a new pylint rule?

http://www.logilab.org/ticket/4983
 
cheers,
-- 
Sylvain Thénault                               LOGILAB, Paris (France)
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