Re: Shortcutting a SAX parser

Hi Michael,

On Mar 31, 2009, at 06:33 , Michael Ludwig wrote:
> It occurred to me that I could shortcut the process by throwing an
> exception to terminate the parser once the data is harvested, catch  
> the
> exception, and then move on to the next document. This is just a  
> trivial
> change to the code:
>
> (1) die in start_element after having collected the data
> (2) protect the parser invocation: eval { $parser->parse_uri( $_) };
>
> As the data I need is at the very start of the document, this is
> significantly faster, even though the documents are only 35 KB on
> average.
>
> Is dying the way to go here? Or is there a more elegant and  
> recommended
> way to terminate the parser? Other thoughts or comments?

Yes, you guessed right (in fact it's documented in http://perl-xml.sourceforge.net/perl-sax/ 
  but I can't get you the exact pointer as my hotel connection is  
horridly slow), that's a perfectly valid approach.

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".

-- 
Robin Berjon - http://berjon.com/
     Feel like hiring me? Go to http://robineko.com/

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