RE: die() without setting $@

[John Deighan]

The problem with trying to use goto, or a return, or setting a global 
variable is that they don't work well in a function that's being called by 
the code that contains the eval. 'return' won't work because it will simply 
return from the function that was called. I don't think that 'goto' will 
work, though you might be able to goto <MODULE>::EOB, I don't know. The 
global variable would still work, but I think that it requires too much 
dependency between the module that the called function is in and the module 
containing the eval. I was hoping for something that works just like die(), 
but didn't set $@, but in the absence of that, I think that perhaps the 
best solution is to do something like die("All is well\n"), then when 
checking for $@ after the eval block, just treat that string as a special 
case. Does anyone see a problem with that?

At 02:28 AM 4/20/2005, Anderson, Mark (Service Delivery) wrote:
perldoc -f goto
eval {
        ...
        goto EOB;
        ...
        ...
        EOB: return;
};if($@){
        ...
}
Kind regards,
Mark Anderson
Service Improvement Programme
Level 2, 113 Dundas Street
Edinburgh, EH3 5DE
Tel: 0131 523 8786
Mob: 07808 826 063
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [SMTP:[EMAIL PROTECTED] On Behalf Of John
> Deighan
> Sent: Tuesday, April 19, 2005 4:57 PM
> To:   perl-win32-users@listserv.ActiveState.com
> Subject:      die() without setting $@
>
> *** WARNING : This message originates from the Internet ***
>
> I need to be able to jump to the end of the enclosing eval block, just
> like
> a die() does, but without setting [EMAIL PROTECTED] Is there a way to do 
that? (I've
> checked the Perl docs, but couldn't find it). I could possibly die() with
> a
> specific string, then use "if ($@ && ($@ ne <string>))" as the error trap,
>
> but that's aesthetically unpleasing.
>
> If you're interested in why, here's the explanation. Our web site is
> implemented via a series of "opcodes". The opcode is passed in the URL.
> There is a goto in our main script that dispatches to a particular opcode,
>
> and the code implementing the opcodes is surrounded by an eval block. When
>
> the output is generated, it's generated via a call to a library that
> outputs a page - usually using a template file. There is, however, also a
> function called errorPage() to which you pass a string. Now, when
> errorPage() is called, there has to be no further HTTP output, so I'd
> prefer, at the end of the errorPage() routine, to pass directly to the end
>
> of the eval block in the main code. die() does just that, but after the
> eval block, there's a "if ($@)" that handles any real errors, like
> database
> connection errors, direct calls to die(), etc., and I don't want calls to
> errorPage() to be treated like true errors (they're "user errors", which
> just means that we want to display a page to the user informing them of
> their error and how to correct it, and errorPage() does just that. Real
> errors result in us receiving an e-mail with the error message, and the
> error being logged to a database table).
>
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