#when:do API

[ELePors]

Hello, when you call a #when:do: on a BlElement, the method calls a #addEventHandlerOn:do: without returning the instance of eventHandler recorded. It must be returned in order do removal on some events handlers.

example :
self when: BlMouseMoveEvent do: [ :event | self mouseMovedTo: event ]
returns the receiver (self) of the message...

[tinchodias]

It happened to me once, I agree we can answer the handler.

Also, I wonder we need an additional change in this API... In Pharo 12, Announcer>>when:do: is deprecated in favor of Announcer>>when:do:for:, with a third argument. I'm not sure if the reason is the ephemerons, or the clean blocks.

@tesonep ?

[labordep]

How to remove a when:do: listener?
when:do: should return the listener to remove it later if necessary.

I propose to do that:

BlElement>>when: anEventClass do: aBlock
	^ self addEventHandlerOn: anEventClass do: aBlock

Of course this on TBlEventTarget trait

[labordep]

After to discuss with @plantec, it's appears than when:do: should be deprecated because this is not symmetric and a little confusing because the add handler is not clear.

[plantec]

instead of when:do: one should use addEventHandler: as in:
clickHandler := (BlEventHandler
on: BlClickEvent
do: [ :event | do something ]).
self addEventHandler: clickHandler.

then one can remove the handler nicely with:
self removeHandler: clickHandler

[labordep]

when:doOnce: is ok because it manage the lifecycle of the event handler itself.