[support] inter module communication, hooks and dependencies

[Pierre Rineau]

I think this is a good idea.

This will let each module set it's own meta keywords and stuffs, like JS
aggregation with drupal_add_js(), something like a meta aggregator hook
or function would be great.

On Fri, 2009-01-02 at 10:56 -0600, Larry Garfield wrote:
> On Fri, 2 Jan 2009 17:42:39 +0100, Ivan Sergio Borgonovo <mail at webthatworks.it> wrote:
> 
> > Of course if what get into head (drupal_set_html_head()) was a
> > structured object rather than a string... I wouldn't have to think
> > to write a module so that each function can easily modify META...
> > but that's another topic...
> > 
> > If there is no core global object and core global workflow and I
> > need one... I wouldn't know how to build it in a module.
> > That's what I'd like to learn.
> > 
> > thanks
> 
> I'd say you're on the right track with a hook.  It's probably easier to explain with examples.  I'd suggest something like:
> 
> hook_meta() {
>   $info['keyword'] = array('foo', 'bar');
> 
>   $info['some_key'] = 'some value';
> 
>   return $info;
> }
> 
> hook_meta_alter() {
>   // Because when you have a structured array, an alter hook is so dead simple to add it seems pointless not to.
> }
> 
> yourmodule_preprocess_page(&$vars) {
>   // Invoke hook_meta_info() and the alter hook, get back the data from all modules, 
>   // format it, and inject it into the $vars['head'] variable as appropriate.
> }
> 
> Modules that need to do complex logic to figure out what tags to add can do so in their own hook_meta implementations.  It also means no module has a hard-dependency on your module or vice versa, weight doesn't matter, and other modules can inject whatever meta tag info they need that you haven't thought of before.
> 
> Make sense?  (Exact implementation is left as an exercise for the implementer.)
> 
> --Larry Garfield
>