Re: Desired behavior for bug #38485: using 'run history' twice

[Daniel J Sebald]

On 03/08/2013 09:48 PM, Daniel J Sebald wrote:
> On 03/08/2013 07:16 PM, Sander van Rijn wrote:
> > Fri 08 Mar 2013 06:00:09 AM CET, *original submission:*
> > <https://savannah.gnu.org/bugs/?38485#comment0>
> >
> > Using 'run history' twice in a row leads to a segfault. The first
> > invocation runs the previous command, whatever it was. The second
> > invocation executes the previous command which is 'run history' and an
> > infinite loop is generated. This isn't a common occurrence, but it isn't
> > great behavior by the interpreter either.
> >
> > Sample Code:
> >
> > disp (1); run history run history
> >
> >
> >
> > What would be the desired behavior in this case? An error about causing
> > an infinite loop or a recursive implementation which would make second
> > 'run history' in the sample code also execute 'disp (1);' ?
>
> I can't replicate this problem. What is "run history" supposed to do?

Oh, run_history, with an underscore.  Yes, I see there is a problem 
there.  I'm inclined to say recursive implementation, but could that run 
into stack issues thereby requiring some error checking also or leave it 
open to potentially crash?  Have to think this one over.

I point out that the help documentation for "run_history" could be 
improved as well.  Anyway, there may be a bug in the run_history whereby 
the most recent history entry can't be accessed by number:

octave:24> history -5
 1048 1
 1049 2
 1050 3
 1051 4
 1052 history -5
octave:25> run_history 1052
error: run_history: history specification out of range

The second most recent can be accessed though:

octave:29> history -5
 1054 6
 1055 7
 1056 8
 1057 9
 1058 history -5
octave:30> run_history 1057
ans =  9

Lastly, the non-argument version of "history" doesn't seem of much use. 
 Is the following what it is supposed to do?

octave:34> history
 1063 history
octave:35> history
 1064 history

I would think that a full listing of history would be a more useful 
thing to display, or at least default the list to, say, 25 entries.

Dan