One thing to consider here is that Announcements are much more of a pattern than a framework. I.e., all it takes is an announcer implementing #on:do: and #announce: and you're ready to go. Given that we have an event hierarchy for system events already, how about using just that?
It would mean that we implement suitable #on:do: and #announce: methods in SystemChangeNotifier and start implementing the proper event handlers in whichever place we feel like, perhaps start in SmalltalkImage as an example of use.
As we migrate away from the old usage, we can make more specific event kinds and get rid of all those awful tests like "(anEvent isRemoved and: [anEvent itemKind = SystemChangeNotifier classKind])" by replacing them by appropriately scoped events, i.e.,
SystemChangeNotifier uniqueInstance on: ClassRemoved do:[...].
This approach also preserves sufficient compatibility as we move forward since all the existing protocols would continue to work.
Cheers, - Andreas
On 8/31/2010 10:31 AM, Eliot Miranda wrote:
Hi All,
I have just found out why some recent images of ours at Teleplacearen't logging doits; the system notifications are missing Smalltalk as a target. If you look at senders of SystemChangeNotifier>>notify:ofAllSystemChangesUsing: in trunk you'll see the following three key senders (ignoring tests)
ChangeSet class>>newChanges: - ensures change sets keep upto date with changes Preferences class>>registerForEvents - ensures prefs stay up to date when methods with preference method tags get added/removed Utilities class>>startUp - ensures recent submissions are maintained
SmalltalkImage is conspicuously absent, yet
| | am | am := (SystemChangeNotifier uniqueInstance instVarNamed: 'eventSource') actionMap. am keys select: [:k| | e | (e := am at: k) isArray ifTrue: [e anySatisfy: [:seq| seq receiver == Smalltalk]] ifFalse: [e receiver == Smalltalk]] #(#protocolRenamedEvent: #methodModifiedEvent: #protocolAddedEvent: #categoryRemovedEvent: #expressionDoItEvent: #methodRemovedEvent: #classReorganizedEvent: #protocolModifiedEvent: #categoryModifiedEvent: #classRenamedEvent: #protocolRemovedEvent: #classRemovedEvent: #classAddedEvent: #categoryRenamedEvent: #classModifiedEvent: #methodRecategorizedEvent: #classCommentedEvent: #methodAddedEvent: #classRecategorizedEvent: #categoryAddedEvent:)
| am | am := (SystemChangeNotifier uniqueInstance instVarNamed: 'eventSource') actionMap. am keys reject: [:k| | e | (e := am at: k) isArray ifTrue: [e anySatisfy: [:seq| seq receiver == Smalltalk]] ifFalse: [e receiver == Smalltalk]]
#(#methodReorganizedEvent: #methodCommentedEvent: #methodDoItEvent: #categoryRecategorizedEvent: #methodRenamedEvent:)
and there's the rub. Why isn't Smalltalk a target of all events? Why does it exclude #methodReorganizedEvent: #methodCommentedEvent: #methodDoItEvent: #categoryRecategorizedEvent: #methodRenamedEvent:? Is this merely accident?
I'm pretty sure that SmalltalkImage class>>startUp needs to ensure system notifications are up-to-date, but are the above exclusions missing for any reason? It's kind of hard to figure out (see below). I *think* that it should read
SmalltalkImage class>>startUp "XXXX: This is broken. SmalltalkImage startUp happens quite late in the startup sequence; earlier startups may very well need the information about the endianness of the platform." EndianCache := nil. SystemChangeNotifier uniqueInstance notify: Smalltalk ofAllSystemChangesUsing: #event:
but I thought I'd check with y'all.
and finally when can we reimplement this entire mess using e.g. Anouncements, I mean:
AbstractEvent>>eventSelector
^self class eventSelectorBlock value: itemKind value: self changeKind
AbstractEvent class>>eventSelectorBlock
^[:itemKind :changeKind | itemKind, changeKind, 'Event:']
Surely this is too direct and easy to understand ;) I mean who /needs/ senders and implementors to work?
grrr.... Eliot