Re: [Sax-devel] RE: SAX-ext proposal #4: feature/property discovery

[David Brownell <david-b@pacbell.net>]

You can implement the "hasXXX" facilities with
the getXXX method:  if calling that throws a
SAXNotRecognizedException, it's not supported.
Otherwise, some value (in some mode) works.

That is, hasFeature()/hasProperty() would just
be syntactic sugar.  I've got a bias against such
stuff, in most cases.

This proposal is for a way to discover/list all the
supported properties/features.  That can't be
replaced by a hasXXX-style API; calling that
for every possible URI is impractical.

- Dave


----- Original Message -----
From: "Michael Brennan" <Michael_Brennan@allegis.com>
To: "'David Brownell'" <david-b@pacbell.net>; <sax-devel@lists.sourceforge.net>;
<xml-dev@lists.xml.org>
Sent: Tuesday, August 07, 2001 4:24 PM
Subject: [Sax-devel] RE: SAX-ext proposal #4: feature/property discovery


> How about just simple "hasFeature" and "hasProperty" methods? Or perhaps
> "supportsFeature" and "supportsProperty". That way code seeking support for
> a particular feature or property can just ask the parser regarding the
> specific feature/property rather than doing a linear search through a list
> for the feature/property in question.
>
> Either way, though, I think this would be a good addition.
>
> > -----Original Message-----
> > From: David Brownell [mailto:david-b@pacbell.net]
> > Sent: Tuesday, August 07, 2001 10:05 AM
> > To: sax-devel@lists.sourceforge.net; xml-dev@lists.xml.org
> > Subject: SAX-ext proposal #4: feature/property discovery
> >
> >
> > Feature/Property discovery
> >
> > - There's no way to find out what features a given XMLReader
> > recognizes.
> >
> >   Given an XMLReader, it's basically possible to find out what values
> >   it supports (modulo when-to-set sequencing constraints) since they
> >   can only be true or false (and might be read-only).
> >
> > - Similarly with properties, though there's no way to determine the
> >   range of values.
> >
> > PROPOSAL:
> >
> >     - Define a new standard property ID:
> >
> >  http://xml.org/sax/properties/supported-features
> >    Read-only
> >
> >    Returns an array of Strings for all the features
> >    supported by this XMLReader.
> >
> >     - Define a new standard property ID:
> >
> >  http://xml.org/sax/properties/supported-properties
> >    Read-only
> >
> >    Returns an array of Strings for all the properties
> >    supported by this XMLReader.
> >