Re: [Bug-apl] Another attention signal issue

[Juergen Sauermann]

Hi Blake,

thanks for that information. Actually the SIGINT is delivered to GNU APL as
expected. The problem is that when I return from the GNU APL SIGINT handler then
readline seems to be blocked in the old readline() call and returns only after another
char (any char - does not have to be newline) was typed.

/// Jürgen


On 07/21/2014 08:21 PM, Blake McBride wrote:

Does this help?

This may be related to the cooked/uncooked/rare terminal modes; ^C does not always send a signal. It seems likely that readline uncooks the terminal, and thus any signals caused by keyboard input must be due to logic within readline itself; it seems plausible that it might only trigger a SIGINT on two sequential ^Cs (especially since for many programs that utilise readline such as shells and REPLs, the program exiting on a single ^C would be very annoying!).

You might be able to change this behaviour by using the readline API to rebind ^C to some of your own code that triggers a SIGINT. I haven't used readline from Haskell, just from C, so I'm not sure exactly how you'd go about this, but the binding seems rich enough to achieve it.

On Mon, Jul 21, 2014 at 12:39 PM, Juergen Sauermann <address@hidden> wrote:

Hi David,

I see. The problem is that the line input (readline) does not return even
though I tell it to (by setting rl_done in the signal handler for ^C). I haven't
found a way to fix this (hints more than welcome). This could also be caused
by terminal settings ("cooked mode") but I thought readline would handle this.

Long term I will most likely replace readline because so far it has created more problems
than it has helped. That would be a bigger issue and should also be aligned with Elias'
emacs mode. So it would  be after the next GNU APL release.

/// Jürgen

On 07/21/2014 06:32 PM, David B. Lamkins wrote:

Thanks, Jüergen.

The real issue, from my perspective, is that APL doesn't report the
ATTENTION message until it sees a newline on input. It seems to me that
typing a ^C should immediately suspend execution and show the ATTENTION
message.

On Mon, 2014-07-21 at 18:23 +0200, Juergen Sauermann wrote:

Hi David,

I have changed readline to display a new line right after ^C, see SVN 382.

For reasons that I don't fully understand, the next character after ^C 
will be eaten by
readline; I tried a number of things to prevent this but haven't succeeded.

I believe readline will be one of the next things removed from GNU APL.

/// Jürgen


On 07/21/2014 02:32 AM, David Lamkins wrote:

When the session is not executing APL code, the attention signal is 
not handled until the next newline.

To see this, enter the characters Control-C, 1, Return.


-- 
"The secret to creativity is knowing how to hide your sources."
   Albert Einstein


http://soundcloud.com/davidlamkins
http://reverbnation.com/lamkins
http://reverbnation.com/lcw
http://lamkins-guitar.com/
http://lamkins.net/
http://successful-lisp.com/