Re: [cgiapp] RE: Changing run modes from another run mode

[Stephen Howard <suppressed>]

oh, well that's good to know.  Do you know of another module out there 
that implements similar semantics without Error.pm's issues?

Kinyon, Rob wrote:

> Error.pm has an intractable memory leak issue regarding closures. I
> would strongly recommend not using this module unless you can guarantee
> you do not generate any closures within the try block.
>
> -----Original Message-----
> From: Stephen Howard [mailto:suppressed 
> Sent: Wednesday, March 24, 2004 10:57 AM
> To: suppressed
> Subject: Re: [cgiapp] RE: Changing run modes from another run mode
>
> Something else you might consider is using the excellent Error.pm module
>
> from CPAN. Then you can do something like this (using rob's subroutine 
> identifiers):
>
> sub A {
>
>   try {
>       sub B()
>   }
>   catch Error with {
>       return sub C()
>   }
>
> }
>
> sub B {
>
>     throw Error('error string') if $bad_condition
> }
>
> Error.pm was designed with propagating errors up the call stack in mind,
>
> so that they can be handled gracefully at the appropriate level.
>
> Kinyon, Rob wrote:
>
>
> > Basically, it sounds like your problem boils down to this:
> > 1) You are in runmode A.
> > 2) You call function B.
> > 3) Within function B, you determine you have error condition C.
> > 4) You now need to switch from runmode A to runmode C.
> >
> > The issue you're running into is the function stack. You have called
> > function B from within function A. You want to change the stack frame
> > for function A into the stack frame for function C. Not so simple.
> >
> > There are a few ways to go about this, some more complicated than
> > others. The easiest one, in my opinion, is to return from function B
>
> two
>
> > values - one that indicates an error has occurred and the other
> > indicating what runmode to call now. Something like:
> >
> >   my ($error, $runmode) = functionB(@parameters);
> >   return $self->$runmode if $error;
> >
> > This method requires runmode A to know that functionB might have
>
> errors.
>
> > It doesn't require runmode A to know that -this- error goes to -that-
> > runmode. 
> >
> > The other solutions tend to be a little more ... complex. I'd try that
> > one first.
> >
> > Rob
> >
> > -----Original Message-----
> > From: suppressed [mailto:suppressed 
> > Sent: Tuesday, March 23, 2004 6:48 PM
> > To: suppressed
> > Subject: Changing run modes from another run mode
> >
> > I have what looks like a fairly simple problem. I have a run mode and 
> > this run mode calls a utility method. The utility method might throw an
>
>
> > error, but the error is fixable. I want my utility method to see if it
> > has an 
> > error and then switch to a specific error run mode to fix the error.
>
> The
>
> > problem is, of course, I can't switch run modes from my utility method,
>
>
> > the only place I can switch is from the cgiapp_prerun method. Whats 
> > the best way to hack around this problem?
> >
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