RFD: Zsh styles and OOP ...

["Andrej Borsenkow" <Andrej.Borsenkow@mow.siemens.ru>]

Unfortunately, no ready-for-implementation ideas ... just some speculations.

To put in general way, styles are used to define properties of objects. Even
if we speak only about completion, there are already more than one sort
(type? class?) of objects there.

1. list of generated matches
2. completion functions (every functions - not just completers)
3. completion system widgets
4. completion system as whole

Each of these classes really has it's own hierarchy (if at all) and should
reasonably have it's own namespace.

Unfortunately, the way contexts are defined currently makes no difference
between different objects putting all of them in single namespace (that
actually is appropriate only for matches list). This gives way to confusing
settings like

zstyle :completion:* completers _complete

that implies, that you can define different copmpleters for diff and gzip,
while completers is actually a property of completion widget(s)

Another example is setting of ps arguments, hosts dastabase, rgb database
and such. I can hardly imagine setup, where kill and killall would use
different settings for ps arguments; or different X commands would use
different rgb or font database. Again, these styles are actually property of
completion system as a whole or at least some helper functions. And in any
case, they are independent of current command, argument position etc.

I believe, it would be of real help to developers as well to

- clear define what sorts of objects exist
- what properties do they have
- use context names, that refelect actual object hierarchy without need of
dummy placeholders or fake "match it all" entries

It would of much help to users if they had context/tags/styles descriprion
divided into subgroups for every object type instead of current long list.

Not sure how interesting it is ...

/andrej