Re: Use of XML for config files

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

Darren New <dnew@san.rr.com> wrote:
: Actually, it maps nicely to
:  <setting key="foo"> bla some value blub </setting>
: which would allow pretty much arbitrary text in the value with minimal
: escapage necessary.

True.
Though line break are not a problem, they will just go away due
to normalization (if that is a problem, then o.K.) (I'm saying this
because I see many people thinking that attribute values are very
restricted, I find this misleading.)

:> This is what attributes are for,
: 
: Well, er, not really, but OK. :-)

o.K, that was a bit loadmothed (by me), but it depends on the
definition of attributes.  SGML/XML attributes aren't required to
be what some people attribute to attributes*) (where some seem
not to be talking of SGML/XML-attributes but about some general
notion of attributes.)  That is, (see Goldfarb/Prescod Sec 54.6)
it is up to the designer of the document type to decide what
to put in attributes and what to put in element content. They
suggest two non-exhaustive guiding criteria:

- attributes cannot contain elements (as you said)
- attributes cannot have occurence indicators

Therefore, if values for keys
- do/don't contain elements...,
- occur exactly once...,
- can e.g. have but "on" or "off" as values,...
  (so  <!ATTLIST feature   value (on | off) on>)

Chose something that meets your purpose.

E.g. when working in 3D-space I can't see anything too wrong with an
"attribute based" matrix, since its structure is fixed and will
stay so:

<!ELEMENT eu3D-trans (row, row, row)>
...
<eu3D-trans>
 <row  x="3.2"  y="14.2"  z="4.1">
 ...
</eu3D-trans>

However, if you insist on a meta-information restriction for
attributes, say, can you handle this case but by the introduction
of some more element types, which, in XML, might become rather noisy?
(Whether the row is the best fit for a eu3D-trans part I don't know)

 *) And never mind whether or not some (probably young and publishing?
:-) computer scientists have superimposed a meta-information model on
XML, there is no need to restrict the capabilities of DTDs just because
some meta-information orientation can be mapped to XML attributes!  :-)

-- Georg