[Laszlo-dev] LzEvent.sendEvent -> sendEvent
jgrandy at openlaszlo.org
Wed Nov 1 09:37:05 PST 2006
On Nov 1, 2006, at 8:22 AM, P T Withington wrote:
> On 2006-11-01, at 10:13 EST, Jim Grandy wrote:
>> On Oct 31, 2006, at 3:07 PM, P T Withington wrote:
>> It's just a really clean mechanism that works well.
> Ok. Hm. Initially, I think I will just pass the event sender as a
> second argument. I'm just trying to limit the size of this
> change. This can easily evolve to an event descriptor in the future.
How would it evolve cleanly? I'd encourage just adding the event
descriptor, even if it has just the event sender in it. This way app
developers can benefit immediately by creating their own event
parameters. Another benefit: classes of events can use the same
parameter names, and so you can write code that processes multiple
types of events generically.
>>> It seems a shame to have to cons up an event descriptor if most
>>> handlers don't need it.
>> I think it's worth it. Plus, in DHTML we could potentially just
>> pass through the HTML event descriptor to save a cons.
> Probably so. But I'm not sure we want to guarantee all the
> information that is in an HTML event descriptor for all platforms.
Well no, we wouldn't guarantee it. It would be a power-user thing,
the equivalent of dropping into ActionScript and using Flash APIs in
>>> It also seems a shame to have to burden all event processing with
>>> the overhead of apply, just so one or two handlers can be passed
>>> multiple arguments.
>>> Should we just add the target as the second argument to handlers
>>> for those who need it, and make handlers that need multiple
>>> arguments use an object?
>>> We could be _very_ clever and look at the number of arguments the
>>> handler expects and create an DOM2-like event object only if the
>>> handler expects a second argument.
>> I kind of like that, but doing that check on every handler in the
>> chain might be expensive...
> It could be done at the time the handler is added to the event. If
> any handler expects the second argument, then the send loop will
> create the descriptor and pass that.
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