Re: Use of XML for config files

[Georg Bauhaus <sb463ba@l1-hrz.uni-duisburg.de>]

Darren New <dnew@san.rr.com> wrote:
: I don't think DTDs allow you to say things like certain values must be
: within certain ranges, etc. If DTDs were that powerful, I'd start to agree
: with you.

They aren't in all cases, that's why people invented schemata,
but for example

<!ATTLIST thing
  switch (on | off) "on"
  connections (1 | 2 | 3 | 4) #REQUIRED
  ident ID #IMPLIED
>

will give you a thing with a switch which is on by default,
with one of two possible values, 4 possible values for a
connection attribute and a unique identifier.

: But I meant something more complex, since I don't think anyone
: wants to teach their users XML DTD syntax to explain that this has to be
: "yes" or "no."

Sure, the idea is, again, that computers will have swallowed
the DTD and people constructing or modifying configuration data
won't be able to enter just about anything.  Depending on whether
there is a specialized configuration application/applet/...
or not, something more complex can be done or not.

:  plus I don't think
: any of the existing Ada XML libraries will validate against a DTD, will
: they?

Afaik, some do. Lots of software libraries available for
binding and studying, e.g. SP, fxp, libxml2, ...