Le 15/10/2012 08:10, Daniel Galdames a écrit :
> That depends on what version of Pharo you use.
> In Pharo 1.4 you can use SystemChangeNotifier to do something like this:
>
> SystemChangeNotifier uniqueInstance
> notify: toSomeObject
> ofSystemChangesOfItem: #class
> change: #Added
> using: #someMethod:.
>
> then if a new class is added to the system, SystemChangeNotifier will
> call #someMethod: on toSomeObject, passing an Event to #someMethod:. You
> can browse the code on SystemChangeNotifier to see all the notification
> you can use, and the package "System-Change Notification" to see the
> events you can receive.
>
> In Pharo 2.0 you can do the same thing using SystemAnnouncer:
>
> SystemAnnouncer uniqueInstance
> on: ClassAdded
> send: #someMethod:
> to: toSomeObject.
>
> You can see the different announcements you can use on browsing the
> package "System-announcements". In this example #someMethod: will
> receive an announcement.
In Pharo 2.0, it could be interesting to use the weak variant of the
subscription.
SystemAnnouncer uniqueInstance weak
on: ClassAdded
send: #someMethod:
to: toSomeObject.
To create a weak link to it.
A convenient method when you develop those things is:
SystemAnnouncer uniqueInstance unsubscribe: toSomeObject.
Because you usually spend time refactoring the #someMethod: above, and
it helps knowing how to remove existing triggers.
And a nice tool is to look at the announcements as they are produced, with
SystemAnnouncer uniqueInstance open
These are the tools I found usefull when tracing the system notifications.
What I missed? A browser able to show who is subscribing to what.
Thierry
> --
> Daniel Galdames
>
> El domingo, 14 de octubre de 2012 a las 20:14, Miguel Enrique Campusano
> Araya escribió:
>
>> I want to do some logic when there is a change on the system, like
>> when a new class is loaded or when a method change. I don't want to
>> put this logic explicit on the methods of the system who do that. I
>> would like to know if i could subscribe to those special events
>> (method change, new method, changes on a class and so on) so I can do
>> what I want outside those methods.
>> I heard about the Announcements but I don't know if Announcements
>> could help with this problem.
>>
>> Can anyone give me some highlights to do those things?
>>
>> Thanks!
>> (I'm really trying with my english, hope it's understandable)
>>
>>
>> --
>> Miguel Enrique Campusano Araya
>> Estudiante de Ingeniería Civil en Computación
>> Universidad de Chile
>>
>
--
Thierry Goubier
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