Re: Need help setting a flag once in sub.m when called from main.m

[Svante Signell]

On Tue, 2010-03-09 at 10:06 +0100, Jaroslav Hajek wrote:
> On Tue, Mar 9, 2010 at 9:29 AM, Svante Signell <address@hidden> wrote:
> > Hi,
> >
> > I have the following problem:
> >
> > I need to call a subfunction once from the main function, setting a flag
> > that it has been called. This should work as long as the workspace is
> > not cleared. I can solve it by a persistent variable in the subfunction
> > but it is not a nice solution.
> >
> > Code below:
> >
> > main.m:
> > <how to declare status here?>
> > status = sub(status);
> > or
> > status = sub();
> >
> 
> persistent status = sub ();

Sorry, setting persistent in the calling script does not work. From my
 understanding it can  only be used in a function.

octave test_sub1.m
warning: ignoring persistent declaration near line 5 of file
`test_sub1.m'

Working code:
==============
% File: test_sub.m
status = "";
printf("Before calling sub\n");
status = sub()
printf("After calling sub\n");

% File: sub.m
function status = sub ();
persistent called;
if (strcmp (called,'y') == 0)
  fprintf ('sub: Entering here once\n');
  called = 'y';
  status = 'yes';
else
  status = 'no';
end%if

Not working code:
=================
% File: test_sub1.m
status = "";
printf("Before calling sub1\n");
persistent status = sub()
printf("After calling sub1\n");

% File: sub1.m
function status = sub1 ();
if (strcmp (status,'yes') == 0)
  fprintf ('sub1.m: Entering here once\n');
  status = 'yes';
end%if

The question was how to avoid the persistent variable in sub.m?