On Tue, Nov 30, 2010 at 2:55 PM, Mariano Martinez Peck < marianopeck@gmail.com> wrote:
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!
AFAIA there are no other ways than in the VM or explicitly, except in the VM simulator ;). best, Eliot
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