[Dev] Menu items support named dispatch

[Donn Denman]

I'll change the attribute name from eventsForNamedDispatch to  
eventsRegisteredByName to avoid the confusion with an event's  
dispatch mechanism.

- Donn

On Aug 2, 2005, at 2:23 PM, John Anderson wrote:

> eventsForNamedDispatch are a list of events for a block. When this  
> block is rendered, these events are added to the list of events  
> that you can dispatch by name. When the block is unrendered, the  
> events are removed the from the list of events that can be  
> dispatched by name. So it controls which events you can dispatch by  
> name. All events, whether refered to directly via a reference or  
> looked up by name are dispatched the same way. Dispatching by name  
> is just another way to find an event which is dispatched like all  
> other event.
>
> All events go to onXXXEvent methods.
>
> Broadcast describes how the event is dispatched, e.g. the event is  
> sent to more than one block
>
> Dispatch-by-name events typically don't go to blocks who have  
> eventsForNamedDispatch
>
> John
>
> Alec Flett wrote:
>> (This is probably more a question for John)
>> I'm not sure I understand the use of eventsForNamedDispatch? this  
>> is something put on the target block that is to receive the event  
>> from the menu item? What dispatch type gets sent to blocks with  
>> eventsForNamedDispatch?
>>
>> If that's the case, then it seems like we have (somewhat, not  
>> completely) redundant named events registration - at least it  
>> seems like:
>> a) "Broadcast" events go to blocks whose classes have onXXXEvent  
>> methods
>> b) "Dispatch-by-name" events go to blocks who have  
>> eventsForNamedDispatch set to the right event.
>>
>> Aren't these effectively the same idea except for the mechanism  
>> used to actually find the target events (Broadcast walks the tree  
>> while I think the other method has some sort of registration  
>> mechanism?)
>>
>> Alec
>>
>> Donn Denman wrote:
>>> Summary
>>> ------------
>>> If you ever create menu items for Chandler, you probably should  
>>> have  an attribute defined for "eventsForNamedDispatch" on your  
>>> MenuItem,  or it won't be accessible from CPIA Script.
>>>
>>> Details
>>> --------
>>> In our dynamic user interface, where blocks come and go, it's  
>>> handy  to have a mechanism that sends an event to whichever block  
>>> is  available to handle that event.  For this reason CPIA has had  
>>> the  ability to dispatch to events using the event's name.  This  
>>> is  implemented as an attribute "eventsForNamedDispatch" on  
>>> Block.   Essentially, this allows the block to publish events  
>>> that it, or its  children blocks, can handle.  This feature has  
>>> not been widely used,  until now.
>>>
>>> CPIA Script is now leveraging off of CPIA's named event  
>>> dispatch,  picking up any events that have been published.  So  
>>> now there's a  second reason to use "eventsForNamedDispatch" on  
>>> blocks you create -  they will be visible to CPIA Script.   I  
>>> have already updated all the  blocks that define events, mostly  
>>> Menu items and Toolbar items, to  publish their events if  
>>> appropriate. In the future, when you're  creating menus, or  
>>> blocks in general, consider if you want your event  to be  
>>> accessible to others, and from CPIA Script.  If you don't want   
>>> your menu to be scriptable, don't add the  
>>> "eventsForNamedDispatch"  attribute, and that will keep your  
>>> event from being directly callable.
>>>
>>> This information will go into the CPIA Author's Guide once we get  
>>> a  chance to write it.
>>>
>>> -  Donn Denman
>>> _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
>>>
>>> Open Source Applications Foundation "Dev" mailing list
>>> http://lists.osafoundation.org/mailman/listinfo/dev
>>
>>
>> _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
>>
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>>

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