SAX RFD: ModSAX Predefined Features

Glenn Vanderburg glv at
Tue Mar 9 15:32:39 GMT 1999

John Cowan wrote:
> >   public abstract void setFeature (String featureID, boolean state)
> >     throws SAXNotSupportedException;
> 2) This method is allowed to throw a SAXNewParserException, which
> encapsulates a replacement parser.

There are two problems with this.

First: let's not use exceptions to report non-error conditions.  There
are theoretical and practical reasons to restrict the use of Java 
exceptions to reporting errors.  (On a related note, I would like to
propose an explicit "boolean featureSupported(String featureID)"
query method to make it possible to test for a feature without risking
an exception.  If anyone would like details of why it's bad to have
exceptions as a part of normal control flow, let me know.)

Second: if an application needs to implement certain features by 
pushing filters from the bottom, it can encapsulate the entire process
on its own, using a composite, and the process never needs to be 
exposed through the ModSAX API.

(I'm new to this discussion, so forgive me --- but let me know ---
if I'm rehashing old debates.)


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