[Pharo-dev] a weak on:do:/when:do:

[Stéphane Ducasse]

whenListChanged: aBlock
        "Specify a block to value after the contents of the list has changed"

        "Basically when you set a new list of items"

        <api: #event>
        | block |
        block := [ :announcement :ann | 
        aBlock
                cull: announcement newContents
                cull: announcement oldContents
                cull: announcement
                cull: ann ].
        listAnnouncer weak
                when: ValueChanged
                do: block