[Q] How should SAX support Namespaces?

John Cowan cowan at locke.ccil.org
Mon Jul 27 16:57:58 BST 1998

Toby Speight scripsit:

> My worry is that if the new interface for namespace-processed elements
> is the same as that for SAX 1.0, then either kind of parser could be
> used in a given program.  But the two types will not return the same
> information through the interface, even though there is no change to
> the function call.  This violates the principle of interfaces and
> programming-to-contract.

Ah.  In my current design, the namespace layer cannot *quite* be
dropped in, because the setParser call (identical to your
second example below) must be done somewhere.
Once that is done, though, other modules need no changes and will get
universal or application-specific names according to their needs.
> OTOH, if namespace processing is an extra layer slotted in, that has
> to be explicitly enabled with something like
>   parser.setNamespaceProcessor(myNameHandler);
> or
>   namespaceProcessor.setParser(myParser);
> then there is no change on the namespace-unaware application, and if a
> namespace-aware application is given a namespace-unaware parser, this
> will be discovered when it tries to enable namespace support.

In effect, yes.  In my model you can use any parser below the namespace
layer (including in principle another namespace layer, though that
is pointless; more realistically a layer of some other kind),
and so parsers proper can remain ns-unaware.

John Cowan	http://www.ccil.org/~cowan		cowan at ccil.org
	You tollerday donsk?  N.  You tolkatiff scowegian?  Nn.
	You spigotty anglease?  Nnn.  You phonio saxo?  Nnnn.
		Clear all so!  'Tis a Jute.... (Finnegans Wake 16.5)

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