Hi everybody,
	I'm doing a research work for my OOD class at university and I'm a
little lost... So I come here looking for your help :) I'm sorry to tell you
that this email is gonna be kinda long, anyway I will try to write only the
most relevant things.

	For this research work I have to write a set of tools that allows
the user to define what should be done when a given object receives a given
message.
	These are examples of what the tools must do:
	- When a given instance of RectangleMorph receives #addMorph: this
should be logged and then the instance finally receives the #addMorph:
	- When any instance of Array receives #add: this message should be
sent to the instance only if the add's argument belongs to a given class.

	I have most of the model finished. But I have problems intercepting
the messages.

	By now I'm only trying to redirect every message to an object of a
fixed class to another fixed object. Both the class of the first object and
the second object are stored in the Special Objects Array. Later I will
replace the receiver with a fixed object that will act as an entry point and
it will redirect the message inside the "object's world" to other objects
that will do all the work.

I have tried two approaches without luck.

1.- Replace the receiver @ Interpreter>>internalActivateNewMethod

I overwrote the receiver after the real receiver and its arguments are
stored:
...
...
"Copy the reciever and arguments..."
argCount2 _ argumentCount.
0 to: argCount2 do:
	[:i | self storePointerUnchecked: ReceiverIndex+i ofObject:
newContext
		withValue: (self internalStackValue: argCount2-i)].

"here comes my code"
rcvr _ self internalStackValue: argumentCount.
self assertClassOf: rcvr is: (self splObj: MRFAux1).
successFlag ifTrue:
[
	self print: 'Intercepting...';cr.
	self storePointerUnchecked: ReceiverIndex+argumentCount ofObject:
newContext withValue: (self splObj: MRFAux2).
].
"and here it ends"
...
...

MRFAux1: Contains the class of the object I want to intercept.
MRFAux2: Contains the receiver.

I guess I'm storing it in the wrong position... I have tried several indexes
without any good result.


2.- Send the message the same way a #doesNotUnderstand is sent @
Interpreter>>lookupMethodInClass: class

When the method is found in the dictionary I just send the message to the
other object creating a message in the doesNotUnderstand fashion:

....
....
found _ self lookupMethodInDictionary: dictionary.
found ifTrue: [
	rcvr _ self internalStackValue: argumentCount.
	self assertClassOf: rcvr is: (self splObj: MRFAux1).
	successFlag ifTrue:
		self print: 'Intercepting @ lookupMethodInClass...';cr.
		self pushRemappableOop: (self splObj: MRFEntryPoint). 
		self createActualMessageTo: (self splObj: MRFEntryPoint).
		rclass _ self popRemappableOop.
		messageSelector _ self splObj: MRFAux2.
		^ self lookupMethodInClass: rclass
	] ifFalse: [
		^ methodClass _ currentClass
	].
].
....
....
MRFAux1: Contains the class of the object I want to intercept.
MRFEntryPoint: Contains the receiver.
MRFAux2: Contains the selector I want to send to the new receiver.

In this case I cant compile the generated code :/

./release/gnu-interp.o: In function `findNewMethodInClass':
//D/J4V13R/SqueakImages/TP/src/3.5.1/win32/gnu-interp.c:3388: undefined
reference to `lookupMethodInClass'
./release/gnu-interp.o: In function `interpret':
//D/J4V13R/SqueakImages/TP/src/3.5.1/win32/gnu-interp.c:6756: undefined
reference to `lookupMethodInClass'

I browse the gnu-interp.c file and the function lookupMethodInClass is
missiong, if I remove the lines I added the code is ok... I have no clue of
what's going on.

Is there a better way to do this? Where any of my ideas right? What was
wrong in their implementation?

Thanks in advance,
	Javier


Some background information:
Squeak Version: 3.6
Virtual Machine: 3.5.1/Tea 1.9 VM (release) from June 21 2003
I've been using Squeak for about 9 months.