[IPython-dev] Wrong line number after exception occurs

[Fernando Perez]

Hi Lee,

On Fri, Sep 3, 2010 at 9:52 AM, Lee Seongjoo <seongjoo.lee at gmail.com> wrote:
> I am not quite sure how to reproduce but wrong line is returned when %rep
> command issued after series of exception occurs. I am pretty positive that
> this is a known issue since I have experienced this unstable line numbering
> quite often. Still, I want to know why and how it happens if possible along
> with its status if anyone could tell me. Thanks.

unfortunately without a reproducible test case that can be automated,
catching something like that will be very, very hard.  I know there's
broken logic with the history synchronization because that state is
managed all over the place, rather than in a single, atomic location.
So when something like an exception breaks the normal execution flow,
it's possible to leave 'dangling' stuff and have the internal state
become inconsistent.

In the work we're currently doing, we're paying a lot of attention to
trying to move various pieces out into independent components, which
should help at least with making problems like these easier to track.
And indeed, we're already seeing the benefits of that from having
kernel and client codes live in independent processes.  But we still
have work to do.

Sorry not to have a more precise answer,  but basically the problem
you have is buried in a rat's nest that I doubt we'll disentangle.
Instead, let's hope our rework gives us a cleaner base where these
problems simply go away.

regards

f