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

[Stephen Howard <suppressed>]

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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