New repository configuration ponderings

[Ralf Corsepius]

On Tue, 2006-05-30 at 00:13 -0700, Panu Matilainen wrote:
> On Tue, 30 May 2006, Ralf Corsepius wrote:
> 
> > On Sun, 2006-05-28 at 20:47 +0300, Panu Matilainen wrote:
> >> On Sun, 2006-05-28 at 19:31 +0200, Ralf Corsepius wrote:
> >>> On Sun, 2006-05-28 at 20:17 +0300, Panu Matilainen wrote:
> >>>> On Sun, 2006-05-28 at 18:20 +0200, Ralf Corsepius wrote:
> >>>>> On Sun, 2006-05-28 at 17:33 +0300, Panu Matilainen wrote:
> >>>>>> I've been thinking about improving the repository configuration and
> >>>>>> related things for a while now. Just yesterday I realized we could
> >>>>>> easily use the existing main configuration system for this, instead of
> >>>>>> inventing yet-another-file-format and parser for it.
> >>>>>
> >>>>> Well, nice proposal, but ...
> >>>>>
> >>>>> ... wouldn't an xml config file format be more suitable?
> >>>>
> >>>> I *hate* XML configuration files from user POV.
> >>>
> >>>
> >>> If xml is suitable for something, then it's parsing config files.
> >>>
> >>> It avoids all the kind of semifunctional implementation nonsense apt's
> >>> and yum's config currently carries around, and would dramatically
> >>> simplify the syntax and a parser's implementation.
> >>
> >> Note the "user POV" in my comment above.
> > Pardon, complete rubbish, IMO.
> >
> > I don't see any substantially difference between
> > <apt>
> >  <cachedir>cache/fedora/</cachedir>
> > </apt>
> >
> > and
> >
> > Apt {
> >  Cache-dir { cache/fedora }
> > }
> 
> Yeah, I know it's not that big a difference, but XML still gives me the 
> creeps when encountered in a human editable file.

Why? Your favorite editor doesn't have an xml-syntax-highlighting mode
but it has an apt.conf-syntax highlighting mode?

>  And I'm not alone with 
> my opinion in that.
And apt's configuration gives me creeps all over the place:
* Where's the grammar?
* Which options do exist?
* When are which options used/set/initialized?

> >>  From programming point of view
> >> I fully agree XML would be much nicer configuration file format. It's
> >> just that XML isn't "human editable" IMO (programmers don't count as
> >> humans here ;)
> >
> > c.f. above.
> >>> But given your attitude, I withdraw my comment above. All your proposal
> >>> does is adding yet another source of errors and of incompatibilities.
> >>
> >> Dunno, apt has a parser which does the job adequately and users are
> >> already familiar with the format.
> > Pardon again, IMO, a very short-sighted POV.
> >
> > apt currently has a swamp of key-values pairs, written in a proprietary
> > block oriented language, hardly with any grammar.
> 
> ...just like 99% of the existing open or closed source software out 
> there :)
Agreed, only very few applications have well designed configuration
languages.

>  It's just yet another bad configuration "language" among other 
> things, at least I'm not inventing a new one here.
> 
> That said, there *would* be significant benefits to using XML, I'm not 
> claiming anything else. What it would take IMO to switch to XML in apt 
> configuration is
> 1) convert *all* of apt configuration to XML
Agreed. If apt's configuration language grammar was well defined, this
would be trivial. As there isn't any formal grammar and as there isn't a
finite set of options, this probably isn't "that easy".

> 2) provide basic tools for manipulating that data without having to touch 
> the xml manually
IMO, this is not fair.

There isn't any tool to provide this feature for current apt's
configuration. So, all you are trying here, is to fight xml by raising
additional demands.

Ralf