[Vm-dev] Problem with Proxies, objects and MethoDict

[Mariano Martinez Peck]

> Anyway, I tried it with
>
> | o p |
> o := MyClass new.
>
> o foo: 123.
> p := ClassProxy new.
> p become: MyClass.
> MyClass flushCache.
> ClassProxy flushCache.
> o == nil.
> Transcript show: o class name; cr.
> o foo.
>
> but same results.
>
> Now, something interesting is that "Transcript show: o class name; cr."
> prints "MyClass". Is this correct?
>
>
Grrrrr no, sorry, that's not true...can you believe there was a "
Transcript cr; show: self name. "  in the fileout code ? heheheh

Now I changed the proxy to extends Class (to see if it works) and at least
it doesn't crash.

"Transcript show: o class name; cr. " prints "a subclass of Object"  and
after the evaluation of the code, I get the error:

MessageNotUnderstood: a subclass of Object>>foo

mmmmm

I will continue investigating....


>
>
>> 2. you became from a class with N inst vars to one with N+M inst vars and
>> the methods of the new class accessed inst vars > N which are off the end of
>> your instance, causing the VM to read invalid oops and boom.
>>
>>
> My case is even more complicated. I want to become from a CLASS to an
> INSTANCE. I mean, I want to become the class MyClass with AN INSTANCE of
> PROXY CLASS. Then the proxy class uses te DNU to bring the other back.
>
> Now I was thinking that maybe the proxy class should not extend from
> ProtoObject but from Behavior or similar?  But I want smaller objects...I
> don't want to spend instances in "uperclass methodDict format'"  since the
> only thing I have to do is with DNU bring back other object.
>
> Finally, I have a question. I tried to look at the #become but I didn't get
> it... When I do a become from a class to an object for example, if there
> were (normal) pointers (slots in other objects) to that class, then they are
> updated and point to the other object. However, what happens with the
> instances of that class?  is the class pointer in their object header
> consider like a normal pointer? are those piointers updated also by the
> #become?    Maybe they are not and this is why  "Transcript show: o class
> name; cr."   prints "MyClass"   ?
>
> Sorry for the newbie question...I am learning all this...
>
> Cheers
>
> Mariano
>
>
>
>> So a) always flush the method lookup cache and b) /never/ cause the VM to
>> read past an object by changing the class underneath an object such that the
>> class accesses more inst vars than the instance has.
>>
>>
>>> how can I solve it ?
>>>
>>> Thanks in advance
>>>
>>> Mariano
>>>
>>>
>>
>>
>
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