[Turn] When exactly does the virtual table pointer (in C + +) gets set for a object?

Ps:http://stackoverflow.com/questions/7934540/when-exactly-does-the-virtual-table-pointer-in-c-gets-set-for-an-object

This is strictly implementation dependent.

For most compilers,

The compiler initializes this->__vptr within each constructor ' s Member Initializer list.

The idea-is-cause each object ' s v-pointer-to-point at its class ' s v-table, and the compiler generates the hidden code F Or this and adds it to the constructor code. Something like:

Base::Base(...arbitrary params...) : __vptr(&Base::__vtable[0]) ← supplied by the compiler, hidden from the programmer { }

This C + + FAQ explains a gist of what exactly happens.

This MSDN article explains it in great Detali

There it says:

"And the final answer is ... as you ' d expect. It happens in the constructor. "

If I might add, right on the beginning of the constructor, before any other code you might has in your constructor gets E Xecuted.

But was careful, let's say you had the Class A, and a class A1 derived from A.

• If you create a new a object, the vptr'll be set right at the beginning of the constructor of the A class
• If you create a new object A1:

"Here's the entire sequence of events when you construct an instance of class A1:

1. A1::A1 calls A::a
2. A::a sets vtable to A ' s vtable
3. A::A executes and returns
4. A1::A1 sets vtable to A1 ' s vtable
5. A1::A1 executes and returns "

[Go] When exactly does the virtual table pointer (in C + +) gets set for a object?