Unsubscribing an event

Hi,

I'm currently playing around with the events mechanism and was
wondering if 'when:' has an 'inverse' method.

If when: (and friends) lets me subscribe to some event notification, is
there a method to unsubscribe me?

Thanks

Fernando,

> I'm currently playing around with the events mechanism and was
> wondering if 'when:' has an 'inverse' method.
>
> If when: (and friends) lets me subscribe to some event notification, is
> there a method to unsubscribe me?

Browse Object, filter to the events category, and look at the #remove*
methods.  You can remove all events, or (probably more useful) all
events triggered for a specified receiver.

Dolphin event mechanism uses weak references, so you seldom need to unhook.

Have a good one,

Bill

--
Wilhelm K. Schwab, Ph.D.
[hidden email]

Fernando,

> I'm currently playing around with the events mechanism and was
> wondering if 'when:' has an 'inverse' method.
>
> If when: (and friends) lets me subscribe to some event notification, is
> there a method to unsubscribe me?

A pointer first.  If you are trying to find a particular method you can
often narrow down the search by using categories.  In this case you know
about the method #when:send:to: so checking for implementors of that
message shows that it's only implemented in Object.  Selecting
Object>>when:send:to: in a browser shows it's category as #events.
Selecting the #events category in the category list tells the browser to
only display methods belonging to that category and includes the following -

#removeAllEventsTriggered
#removeEventsTriggeredFor:

and checking the method comments tells you what their purpose is.

#removeAllEventsTriggered will remove all the events that the receiver
triggers.

You are more likely to want the second, #removeEventsTriggeredFor: which
removes all the events registered for a particular target

...
aClass when: #whatever send: #something to: whoever
...
aClass removeEventsTriggeredFor: whoever

What you _can't_ do in the base image, and I've had to add it myself
when needed, is to remove specific events

aClass removeEvent: #whatever triggeredFor: whoever

--
Ian

Use the Reply-To address to contact me.
Mail sent to the From address is ignored.

Fernando,

> I'm currently playing around with the events mechanism and was
> wondering if 'when:' has an 'inverse' method.
>
> If when: (and friends) lets me subscribe to some event notification, is
> there a method to unsubscribe me?

A pointer first.  If you are trying to find a particular method you can
often narrow down the search by using categories.  In this case you know
about the method #when:send:to: so checking for implementors of that
message shows that it's only implemented in Object.  Selecting
Object>>when:send:to: in a browser shows it's category as #events.
Selecting the #events category in the category list tells the browser to
only display methods belonging to that category and includes the following -

#removeAllEventsTriggered
#removeEventsTriggeredFor:

and checking the method comments tells you what their purpose is.

#removeAllEventsTriggered will remove all the events that the receiver
triggers.

You are more likely to want the second, #removeEventsTriggeredFor: which
removes all the events registered for a particular target

..
aClass when: #whatever send: #something to: whoever
..
aClass removeEventsTriggeredFor: whoever

What you _can't_ do in the base image, and I've had to add it myself
when needed, is to remove specific events

aClass removeEvent: #whatever triggeredFor: whoever

--
Ian

Use the Reply-To address to contact me.
Mail sent to the From address is ignored.

Hi,
"Ian Bartholomew" <[hidden email]> wrote
> What you _can't_ do in the base image, and I've had to add it myself when
> needed, is to remove specific events
>
> aClass removeEvent: #whatever triggeredFor: whoever
I'd like to learn how to implement this intricate method to ehhance my st
knowledge in Dolphin event mechinery stuff.


regards,
tkkuo