Re: [relax-ng] ooRelaxNG (was: Limitation ...)

[John Cowan <cowan@mercury.ccil.org>]

MURATA Makoto (FAMILY Given) scripsit:

> In o-o programming languages, we have variables, classes, and objects.  

To be sure, but in XML (which is data, not code) we have no analogues
of variables.  We have only class literals, where we say "Create an
object of class foo with attributes bar and child objects baz".
The RNG schema tells us whether this object, said to be of class foo,
is or is not conformant to the constraints placed on foo-class objects.

> By the way, the XML Schema WG thinks that representing both variables 
> and classes in the instance is redundant.  Thus, they omitted class 
> names.

And I agree, or rather I think that variables have no place here.

> The class declared for a variable is determined from the 
> variable name, but the class bounded to this variable cannot be determined.
> In the example, we can find the class Foo from the variable foo, but cannot 
> know that this instance is of the class Bar.  To remedy this problem, 
> the XML Schema WG introduced xsi:type.  I think that this is disastrous.

I still don't understand this, unfortunately.  Can you clarify further?

-- 
John Cowan           http://www.ccil.org/~cowan              cowan@ccil.org
To say that Bilbo's breath was taken away is no description at all.  There
are no words left to express his staggerment, since Men changed the language
that they learned of elves in the days when all the world was wonderful.
        --_The Hobbit_