Hello.
I finished new version of Ghost:
- DNU approach for basic proxies instead of #cannotInterpret: trick
(trick used only for class proxies)
- Abstract proxy classes uses Ghost name instead of Proxy: there are
GHObjectGhost and GHClassGhost.
- GHProxyHandler renamed to GHGhostBehaviour. Concrete ghosts should
implement #ghostBehaviour instead of #proxyHandler.
- GHGhostBehaviour should define #currentMetaLevel to specify set of
messages which should not be intercepted. Such meta messages will be
executed under ghost instance by subclass of GHMetaMessages.
In previous version there was dictionary which maps meta message selector
to implementation selector. It was not suitable. Now meta messages should
be directly implemented on particular GHMetaMessages subclass and all it
methods are considered meta.
So GhostBehaviour should return instance of GHMetaLevel with meta messages
implementation class:
- GHMetaLevel with: GHEmptyMetaMessages "when all possible messages
should intercepted"
- GHMetaLevel with: GHStandartMetaMessages "when tools specific
messages should not be intercepted"
For example standard meta messages implements #inspect:
GHStandartMetaMessages>>inspect
"Create and schedule an Inspector in which the user can examine the
receiver's variables."
^ Smalltalk tools inspector inspect: *ghost*
- Traits for methods explicitly defined on ghosts: TMinimalProxy,
TNotNilProxy, TIdentifiedProxy (with #=, #hash, #class). Concrete proxies
can add this traits to itself independently from meta level. For example
traits supply convenient methods to retrieve ghost information in
polymorphic way with objects:
- ghost isGhost
- ghost ghostClass "returns actual class of receiver"
- ghost ghostPrintString "returns string which represents ghost from
meta level point of view"
This traits are suitable and they provide some kind of optimisation for
proxies (methods from traits are executed directly instead of complex meta
messages mechanizm). But maybe they are superfluous. For example they can't
be reused for class proxies which substitute real object classes (to
intercept all instance messages).
- GHClassGhost able to replace class of real objects. It implements
cannotInterpret: trick to intercept all instance messages. Subclasses
should define two behaviours: #ghostBehaviour (as any other ghost) and
#instancesBehaviour which will process instance messages. In previous
version it was different message to same #ghostBehaviour.
- New kind of proxies:
- GHObjectVirus. It is special kind of GHClassProxy. It infects real
object to intercept it messages. From meta level infected object
looks like
healthy object which means that meta messages are executed by infected
object itself. As class virus looks like real victim class. So
in case when
virus is created with standard meta level tools will not differ him from
health object. There are special messages which allow ask object about
viruses:
- infectedObject isInfectedByVirus
- infectedObject virus
- infectedObject recoverFromVirus
- GHLearningObject. It is suitable proxy which retrieves all unknown
methods from teacher class. Thank's Stephan for this idea.
This kind of proxy allows me easily find required set of messages to
support inspectors and debuggers. You can create instance of learning
object by:
GHLearningObject withTeacher: Object.
And any operation with it will fill studiedMessages dictionary. In my case
I opened GTInspector on it and got all messages which was needed for him.
- Ghosts works correctly with latest Pharo 5 tools (basic inspector,
GTInspector, SpecDebugger, GTDebugger). Required methods for tools are
extracted to 'Ghost-GTSupport' package.
- Repackaging:
- Ghost-ObjectProxies. It contains all core classes and abstract
GHObjectGhost which is based on DNU
- Ghost-ClassProxies. It contains code for proxy which can substitute
class of real object. GHClassGhost implements cannotInterpret: trick to
intercept all instance messages. And it implement support for debugging
such methods.
- Ghost-LearningObject
- Ghost-ObjectVirus
- Ghost-GTSupport
- test packages
- All code moved to Pharo repository
http://smalltalkhub.com/#!/~Pharo/Ghost (in includes packages from CAR
repo too)
You can load new version by:
Gofer it
smalltalkhubUser: 'Pharo' project: 'Ghost';
configurationOf: 'Ghost';
loadStable
I use it now in Seamless and Mocketry.
