Variable offset and multi inheritance

[bergel]

Hello,

Regarding the variable layout with multi inheritance, I looked into a
couple of C++ books but I was not able to find a descent answer.
Let assume I have the following:
class A{
int x;
}
int A::getX(){ return x;}

class B{
int y;
}
int B::getY(){ return y;}

class C: virtual A, virtual B {
}

In A the offset of x is 0. Same thing for B, the offset of y is 0.
But what is the variable layout of C?
If x'offset = 0 and y's offset = 1, what's happen with the getY()
method ? Is it duplicated to take the new offset into account ? Or is
there any dynamic lookup of variables ?

Cheers,
Alexandre

[Artie Gold]

bergel wrote:

Hello,

Regarding the variable layout with multi inheritance, I looked into a
couple of C++ books but I was not able to find a descent answer.
Let assume I have the following:
class A{
int x;
}
int A::getX(){ return x;}
No such function has been declared.
class B{
int y;
}
int B::getY(){ return y;} Similarly.
class C: virtual A, virtual B {
}

In A the offset of x is 0. Same thing for B, the offset of y is 0.
But what is the variable layout of C?
If x'offset = 0 and y's offset = 1, what's happen with the getY()
method ? Is it duplicated to take the new offset into account ? Or is
there any dynamic lookup of variables ?

Cheers,
Alexandre

Important question: Why do you care?

This is a question about `under the hood' implementation, not one about
the C++ language itself.

--ag

--
Artie Gold -- Austin, Texas
http://it-matters.blogspot.com (new post 12/5)
http://www.cafepress.com/goldsays

[bergel]

Because I am interested in muti-inheritance mechanism.

Alexandre

--
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Alexandre Bergel http://www.iam.unibe.ch/~bergel
^~:;._,.;:~^~:; ._,.;:~^~:;._,. ;:~^~:;._,.;:~^ ~:;.