Re: localtraps

[Vincent Stemen <zsh@xxxxxxxxxxx>]

On Wed, Apr 27, 2005 at 05:59:07AM +0000, Bart Schaefer wrote:
> On Apr 26,  5:12pm, Vincent Stemen wrote:
> }
> } One thing I tried was to set a flag indicating that the signal had
> } already hit once so that when it re-calls the sig handler it would
> } know it was the second time.  That did not work though for the same
> } reason.  I cannot reset the flag before exiting the function because
> } it always completes the function before processing the next signal and
> } re-calling it.  So on the next signal, the flag is always back unset.
> 
> This should work with a sufficiently recent version of zsh to have the
> "always" construct:
> 
>     inner () {
> 	if ((trips++))
> 	then
> 	  {
> 	    print "Do the multiple-trip thing ..."
> 	  } always {
> 	    ((--trips))
> 	  }
> 	fi
>     }
> 
>     outer () {
>       {
> 	setopt localoptions nolocaltraps
> 	integer -g trips=1
> 	trap inner INT
> 	print "Doing something useful now ..."
> 	sleep 2
>       } always {
> 	unset trips
> 	trap outer INT
>       }
>     }
>     trap outer INT
> 
> With that, even if I press ^C and hold it down, it alternates between
> "Doing something useful now ..." and "Do the multiple-trip thing ..."
> and ends up with "trips" unset.  Of course, this is on Linux; if you
> are right about the NetBSD signal behavior, you'll need something more
> subtle.

I added a sleep at the end to give me time to hit ^C and tested on
NetBSD.  Here is the result.

# sigtest
^CDoing something useful now ...
^C^C^C^C^CDoing something useful now ...
^C^C^CDoing something useful now ...

Which is pretty much what I expected since I cannot reset the trap
in the sig handler.

-- 
Vincent Stemen
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