Diego,

You are my guy...

:-)

Alexandre changed the VM recently for his ClassBoxes
http://scgwiki.iam.unibe.ch:8080/SCG/559
so there is hope...

I am into test-composition, which would be possible,
if you had concrete pre-/postconditions put as assertions
into real instance-methods and _not_ in some external
test-methods.
See http://minnow.cc.gatech.edu/squeak/2996

Cheers,

Markus
--
Markus Gälli				   Software Composition Group
markus.gaelli at iam.unibe.ch	University of Bern, Switzerland
Office: +41(0)-31-631-3313		Fax: +41(0)-31-631-3355


> Hi Stef,
>
> I think you know my feeling.  WE NEED MORE RESEARCH!!!
>
> Let's go for the next step!  What one is the next-step? I don't know at
> all...  But we can't stay on the same state as 20 years ago.
>
> IMHO, there are a lot of thing to try-to-improve so we need a better
> environment to test ideas.  Let me explain some ideas [*]
>
> Method Dictionaries in the object level (a la Visual-Smalltalk)
>
> - Replace the class reference in each object to a reference to a
> MethodDictionaryCollection
>
> - Each object has a collection of superclasses (the superclasses 
> chain).
> Each class has one MethodDictionary.  Each object has the collection 
> of all
> the MethodDictionaries of all its superclasses.
>
> Example:
>
> Superclass3
>   Superclass2
>     Superclass1
>       TheClass
>
> Each of these classes has one MethodDictionary.  oneInstanceOfTheClass 
> has
> a collection of methods dictionaries like {TheClass methodDictionary.
> Superclass1 methodDictionary. Superclass2 methodDictionary. Superclass3
> methodDictionary}.
>
> The collection CAN be shared between all instances of the class.  The
> method dictionary of each class MUST be the same for any object that 
> has
> the class in the superclass-chain.
>
>  testPriorSentence
>     "unit test to show the prior sentence written in poor english"
>     | allInstances |
>     allInstances := Object allSubInstances.
>     self
>        should: [
>           allInstances
>              allSatisfy: [:eachInstance |
>                 | superclassesChain methodDictionariesChain |
>                 superclassesChain := eachInstance class 
> withAllSuperclasses.
>                 methodDictionariesChain := superclassesChain
>                          collect: [:eachClass | eachClass 
> methodDictionary].
>
>                 eachInstance methodDictionaryCollection =
> methodDictionariesChain]]
>
> With this approach we have exactly the same behavior we have today. 
> But...
> we can put in the MethodDictionaryCollection one more entry for 
> instance-
> specific-behavior (or more than one to have super-instances a la Self).
>
> The VM has to be modified to look over the MethodDictionaryCollection
> instead of using the class.
>
>
> The other change is to "hack" the VM to check is the
> MethodDictionaryCollection is a real MethodDictionaryCollection.
>
> - If it's a real one: The normal method look-up is used.
>
> - If it is NOT a real MethodDictionaryCollection: The object (the one 
> in
> place of the MethodDictionaryCollection) is asked for the method with 
> some
> normal smalltalk message (example: #methodForSelector:andReceiver:).  
> Then,
> the result of the prior message is "evaluated" with another normal 
> message
> (example: #evaluateOnReceiver:context:).
>
> With these *relative* simple changes to the object struct and the VM, 
> we
> open the door to research a lot of alternatives:
>
> - different methods lookups
> - behaviour in object level
> - different type of method activation (examples: accesors a la Self,
> MethodComposites, pre and post conditiona a la Eiffel, etc)
>
>
> Just my 2 cents,
>
> Diego Gomez Deck
>
>
> [*] Thanks to Alejandro Reimondo for infect me with these ideas!
>
>
>
>
>