Re: [LAD] "enhanced event port" LV2 extension proposal

On Wed, 2007-12-05 at 22:50 -0500, Dave Robillard wrote:
> On Wed, 2007-12-05 at 04:35 +0100, Lars Luthman wrote:
> > On Tue, 2007-12-04 at 09:42 +0000, Krzysztof Foltman wrote:
> > > What about this (translate it to C in your heads :) ):
> > >
> > > interface IURIRegistryObserver
> > > {
> > > // function in plugin etc. called by host whenever new URI is registered
> > > void mapping_added(int id, const char *uri);
> > > };
> > >
> > > interface IURIRegistry
> > > {
> > > int uri_to_id(const char *uri, bool create_if_absent);
> > > const char *id_to_uri(int id);
> > > void add_observer(IURIRegistryObserver *observer);
> > > void remove_observer(IURIRegistryObserver *observer);
> > > };
> > >
> > > interface IURIRegistries
> > > {
> > > IURIRegistry *get_registry(const char *registry_uri);
> > > };
> >
> > I don't like having something this complicated in an extension that is
> > going to be required if you just want to write a simple synth with a
> > MIDI input. Is there really any need for adding and removing mappings
> > dynamically?
>
> Definitely agreed.
>
> > Just passing an array in the LV2_Feature data would be enough for me.
>
> Simple is nice, but somewhat closed ended.
>
> How about simply passing a function pointer which converts a string to
> an int? (in a Feature struct so things can be added for a more advanced
> symbol system in the future)
>
> Easier on the plugin author to just call a function than have to
> implement that search all over the place anyway.

That sounds OK. I suggest something like this:

struct URI_Mapper {
  // call this with your URI and the host_data member - not RT safe
  uint16_t (map_function*)(const char* uri, void* host_data);
  // pass this as the second parameter to map_function()
  void* host_data;
};

It doesn't provide a way for the host to say "I'm out of IDs!" though.
Will that be needed?

--ll

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