Re: [libxml++] [Fwd: DTD validation for libxml++]

[Jonathan Wakely <cow compsoc man ac uk>]

On Wed, Mar 31, 2004 at 05:16:12PM +0200, Christophe de VIENNE wrote:

> Date: Wed, 31 Mar 2004 16:33:06 +0200
> From: "Guillaume Arreckx" <bill arreckx acterna com>
> To: cdevienne users sourceforge net
> Subject: DTD validation for libxml++

[snip]

> To valide an xml document, all the user has to do is :
> 
> try
> {
>    xmlpp::DtdValidator validator( dtdFileName );
>    xmlpp::Document *pDoc = ...
>    validator.validate( pDoc );
> }
> catch( const xmlpp::parse_error& )

Nice.

Should DtdValidator.validate() throw something other than parse_error ?

A new xmlpp::validation_error type maybe ?

Otherwise distinguishing between not well-formed and not valid requires
something like:

    try
    {
       xmlpp::DtdValidator validator( dtdFileName );
       xmlpp::Document *pDoc = ...
    }
    catch( const xmlpp::parse_error& )
    {
       // DTD or document is not well-formed
    }
    try
    {
       validator.validate( pDoc );
    }
    catch( const xmlpp:parse_error& )
    {
       // document is not valid
    }

as opposed to:

    try
    {
       xmlpp::DtdValidator validator( dtdFileName );
       xmlpp::Document *pDoc = ...
       validator.validate( pDoc );
    }
    catch( const xmlpp::parse_error& )
    {
       // DTD or document is not well-formed
    }
    catch ( const xmlpp::validation_error& )
    {
       // document is not valid
    }

The exception handling in the first example reduces readibility, rather
than moving error-handling away from the business logic.

Just a thought,

jon


-- 
"A scientific theory should be as simple as possible, but no simpler."
	- Albert Einstein