[compiz] meta data update

[Danny Baumann]

Hi,

> Plugin dependencies have not yet been moved to the meta data system. I'd
> like some feedback before we do this. I suggest that we use tags similar
> to this:
> 
> <compiz>
>     <plugin name="cube">
>         <feature>large-desktop</feature>
>         <deps>
>             <requirement>
>                 <plugin>png</plugin>
>                 <feature>some-feature</feature>
>                 <some_property>name-of-required-property</some_property>
>             </requirement>
>             <conflict>
>                 <plugin>plane</plugin>
>                 <feature>some-other-feature</feature>
>             </conflict>
>         </deps>
>     </plugin>
> <compiz>
> 
> It will make it easy to add new meta data tags that can be used as
> requirements or conflicts.

Sounds good. What I am missing in your suggestion, however, is the
definition of load order hints. Following your suggestion for
requirements & conflicts, I would suggest the following:

<compiz>
    <plugin name="someplugin">
        <loadorder>
            <before>someotherplugin1</before>
            <after>someotherplugin2</after>
        </loadorder>
    </plugin>
</compiz>

> The other thing that needs to be discussed related to this is whether
> the core should be aware of any of these dependencies. I think that not
> having the core be aware of any dependencies is definitely the best
> solution. It's up to the plugins to deal with conflicts. Whether that is
> to fail when loading or lack functionality doesn't matter but they will
> of course not be allowed to crash.

Sounds fine to me.

Regards,

Danny