Re: Hang on incomplete input

[Nick Dokos <nicholas.dokos@hp.com>]

Ken Williams <Ken.Williams@windlogics.com> wrote:

> 
> Rafael wrote:
> 
> > In Ubuntu 10.10, emacs 23.2 and recent org, I get an *Org-Babel Error
> > Output* buffer, saying:
> >
> > Error: unexpected '}' in:
> > "ddply(x,
> > }"
> > Execution halted
> 
> I'm using:
> 
> GNU Emacs 23.3 (from http://vgoulet.act.ulaval.ca/en/emacs/windows/)
> Windows 7
> org-mode 7.7
> ESS 5.14
> 
> What version of ESS do you have?  Maybe that's the difference?
> 

FWIW, I got the same thing as Rafael:

Linux 2.6.35-28-generic #50-Ubuntu SMP Fri Mar 18 18:42:20 UTC 2011 x86_64 GNU/Linux
GNU Emacs 24.0.90.2 (x86_64-unknown-linux-gnu, GTK+ Version 2.22.0) of 2011-10-27
Org-mode version 7.7 (release_7.7.617.gb1f2)

Forgive my ignorance: how do I check the ESS version? And what does ESS have
to do with R? I thought this was an R code block, but as you can probably
tell, I'm an ignoRamus.

When I start R interactively, I get 

,----
| R version 2.11.1 (2010-05-31)
| Copyright (C) 2010 The R Foundation for Statistical Computing
| ISBN 3-900051-07-0
`----

> Any suggestions for how to debug a hang like this?  Is there a signal I can send it, to generate a stack trace (if signals are even possible in Windows, I'm not even sure)?
> 

Probably the best thing to do is cut out the middleman: execute the code
snippet in the appropriate environment directly - no emacs, no org, no
babel - and see if you have the problem. There are differences of course
that babel tries to minimize but it can only simulate certain cases. E.g
when I enter the incomplete form in the interactive session, it keeps giving
me a secondary prompt attempting to convince me to do something sensible:

,----
| 
| >  dply(x,
| + 
| + 
| + )
| Error: could not find function "dply"
| >
`----

babel does not have that luxury.

If that does not bear fruit, you can M-x toggle-debug-on-quit, run the
code block and press C-g to get a backtrace. Rinse, repeat to see
whether you always stop at the same point. It's somewhat hit-or-miss but
it can be effective sometimes.

Nick