On Tue, Nov 30, 2010 at 11:45 PM, Eliot Miranda <eliot.miranda@gmail.com> wrote:

On Tue, Nov 30, 2010 at 2:33 PM, Mariano Martinez Peck <marianopeck@gmail.com> wrote:

Thanks to both for answering me.
Now, I have very very newbie question.
In my case, JUST BECAUSE i am testing, I directly access the CompiledMethod using MethodDictionary >> #at:ifAbsent:
thus, I can intercept and load back the original proxy.

Now, if I understood well, when you send a simple message to an object, the method lookup is done at VM side, and there is no call to MethodDictionary >> #at:ifAbsent:

So, what I am saying is that someone (the system) can send messages to a SmallInteger that acts as a compiled methods, without accessing it by MethodDictionary >> #at:ifAbsent:.
If that message is understood by the SmallInetger, then it will probably answer something different than the original method.

You're forgetting that the VM executes the methods it finds in a method dictionary, except if the VM finds other than a CompiledMethod in a method dictionary, in which case it sends run:with:in: to it. �So the VM won't send anything to the SmallInteger method proxy other than run:with:in:. �If it didn't send run:with:in: it would crash trying to execute the SmallInteger.

I think we are confusing exatly like we were confusing yesterday with my supervisors.

Eliot, one thing is to do this:

MyClass methodDict at: #foo put: 5.
MyClass new foo.

Here I am SURE the VM will send #run:with:in to SmallInteger.

Now, my question is when I send a MESSAGE to the CompiledMethod, and NOT to the object which class has installed the compiled method.

Suppose I do:� (MyClass methodDict at: #foo) size.�� and that I don't change the implementation of MethodDictionary >> #at:ifAbsent:

In this case, the VM will just try to send the message size to that whatever is there. Both, SmallInteger and CompiledMethod understand #size, but both answer different things...
I cannot intercept this, and I cannot load back the original object.

This is why with Levento we thought about modifying MethodDictionary >> #at:ifAbsent:� to something like this:

at: key ifAbsent: aBlock

�� | index value |
�� index := self findElementOrNil: key.
�� (self basicAt: index) == nil ifTrue: [ ^ aBlock value ].
�� value := array at: index.
�� (value mareaIsProxy) ifTrue: [value mareaUninstall].
�� ^ array at: index

But then, my question is if the system may access by another way than that one. Ok, I should also modify some other methods in MethodDictionary like #valuesDo:� etc,,,
but if I do that, is that enough?�� or the system can still send messages without passing there?

Thanks a lot!

mariano

�

best
Eliot

Now, maybe what I am thinking cannot happen.

Thanks once again

Mariano

On Tue, Nov 30, 2010 at 10:23 PM, Levente Uzonyi <leves@elte.hu> wrote:

On Tue, 30 Nov 2010, Igor Stasenko wrote:

.. and then you need to change #do: , #associationsDo: etc etc..

Or he can subclass MethodDictionary and override those methods.

Levente