Hello Igor,

thank you for your interesting explanations!

One remark:

On 28.02.2008 09:04, Igor Stasenko wrote:
> John M McIntosh asked me to make some overview on HydraVM internals -
> events subsystem.
> So, here it is. :)
> 
>...
> About event handling function:
> this is the function which will be called when interpreter will
> interrupt for handling events, so in this function you have
> synchronized access to object memory, interpreter state e.t.c. and
> don't have to worry about concurrency.
> Also, function along with event payload are very convenient for
> determining context and what event means and what it will do.

> Instead of making dozens of event types, enumerating them.. then
> writing a case statements, it's doing a simple dispatch
> event->fn(interpreter, event); so, system are flexible and can handle
> events of any kind doing anything you want.

This makes it possible to elegantly switch between different event handling funcs: e.g. between a normal and a debugging one, without *any* debugging code in the normal one (by an event func var in the plugin, set by a plugin primitive, used by event posting code).


Regards,
Stephan

> 
> As for example, suppose you wanna write a plugin which needs to post
> events to interpreter, but with your own, custom handling code, and
> with your event payload.
> So, declare an event in form:
> 
> struct myEvent
> {
>   struct vmEvent header;
>   int myField1;
>   int myField2;
>  ..
> };
> 
> Now to post event we simply can do:
> 
> myEvent * event = malloc(sizeof(myEvent));
> event->header->fn = myHandler;
> event->myField1 = ...
> ....
> 
> Now, a handler function:
> 
> sqInt myHandler(struct Interpreter * intr, myEvent * evt)
> {
>    ... do something nasty here, knowing that you can't be trapped by
> concurrency issues :)..
> 
>   free(evt); // release memory, allocated for event
> }
> 
> 

-- 
Stephan Rudlof
   "Genius doesn't work on an assembly line basis.
    You can't simply say, 'Today I will be brilliant.'"
    -- Kirk, "The Ultimate Computer", stardate 4731.3