Re: [Ongui-dev] event model

[Robin R. <ro...@Mo...>]

Mike,

> ...I started a new job among other things.

That's great! Congratulations!

> On a lighter note, I think I've now convinced myself that your
> "simple" event model will work even for advanced applications
> (initially I was hesitant, if you remember, and was considering
> pushing a listener event model). So: never mind. Consider me a
> convert.

Whoo hoo! Glad to hear that!

My issue with listener architectures is they expose users to too much
plumbing. The OnGui model as implemented in the gfx prototype is not as
restrictive as it seems at first glance. There are three mechanisms
implemented in the architecture to enable covering all event contingencies
efficiently:

1.) The ususal case where you want to catch the dozen or so typical GUI
events. Applies 98% of the time. In OnGui the generic event model just
magically is there, no plumbing. Simply call the virtual On handler for your
event. However, what if you need to catch an atypical event without a
specific On handler in the generic model?

2.) The case where you want an atypical event in addition to the typical
events. There is a catch-all On handler at the bottom of the generic event
system. You can trap it there easily. But, what if that is too inefficient?

3.) The case where the catch-all handler and generic event system invoke too
much overhead, that you only want to catch specific events, to tune the
event model for maximum performance. In that case you write your own master
event handler and call the method that installs that in place of the generic
master handler for that window. Gives full access to plumbing when you need
it.

> In any case, I know we briefly discussed what low-level library to
> use. If you have no objections, I'd like to initially use GDK, since
> this is already ported (or being ported) to the platforms you
> specified.

I think you are right. Proceed using GDK unless we discover a strong reason
not to.

Cheers,

Robin
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