Re: Shortcutting a SAX parser

From:           	Michael Ludwig <[email protected]>
> Robin Berjon schrieb:
>    http://perl-xml.sourceforge.net/perl-sax/sax-2.1.html#Exceptions
>    perldoc XML::SAX::Exception
> 
> > If you want to be absolutely strict and defensive in your programming,
> > you probably want to throw a specific exception (SAX exceptions are
> > expected to have at least a Message key with a reason for throwing)
> > and check that that's the one you're getting. That way, if your
> > document does turn out to have a problem, your code won't confuse
> > "threw because I got what I wanted" with "threw because something
> > smells bad".
> 
> That's true, of course you really should do that. However, two things
> combine to make this difficult.
> 
> First, after a die(), the $@ variable also contains (from the point of
> view of the program logic) random line number information, which, in a
> hackerish manner, you'd then have to weed out in order to compare the
> string to the expected one.
> 
>    eval { die 'Gurke' };
>    print $@ if $@;

Compare

    eval { die "Gurke\n" };
    print $@ if $@;


> Second, the documentation I referred to above does not describe the
> behaviour I'm observing. $@ is not a blessed hash reference, but a
> simple string. Maybe that has to do with the fact that the class
> overloads "", but then, I don't know how to get at the object.

  use XML::SAX::Exception;
  @XML::SAX::Exception::Done::ISA = ('XML::SAX::Exception');

  use Data::Dumper; 
  eval { throw XML::SAX::Exception::Done( Message => 'Doc done' ); };
  print Dumper($@) if $@;

seems to work for me. If it doesn't for you, someone must be catching 
and rethrowing the exception and stringifying it along the way.

Jenda
===== [email protected] === http://Jenda.Krynicky.cz =====
When it comes to wine, women and song, wizards are allowed 
to get drunk and croon as much as they like.
	-- Terry Pratchett in Sourcery

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