*this in initializer list

[Alexander Stippler]

I know using this in a class initializer list has to be dealt with with
care. I fear for "*this" it is even worse. Is it legal at all - what
does the standard say?
My situation is somewhat like:

struct B;

struct A
{
A(const B &_b) : b(_b) {}

const B &b;
};

struct B
{
B() : a(*this) {}
A a;
};

I just want this reference. No member access or similar (in the
construction process).
Allowed (and reasonable?) by standard or not?

best regards,
Alex

 

[peter koch]

I know using this in a class initializer list has to be dealt with with
care. I fear for "*this" it is even worse. Is it legal at all - what
does the standard say?
My situation is somewhat like:

struct B;

struct A
{
        A(const B &_b) : b(_b) {}

        const B &b;

};

struct B
{
        B() : a(*this) {}
        A a;

};

I just want this reference. No member access or similar (in the
construction process).
Allowed (and reasonable?) by standard or not?

best regards,
        Alex

This is perfectly safe and allowed in the standard.

/Peter

 

[Marcel Müller]

struct B;

struct A
{
A(const B &_b) : b(_b) {}

const B &b;
};

struct B
{
B() : a(*this) {}
A a;
};

I just want this reference. No member access or similar (in the
construction process).
Allowed (and reasonable?) by standard or not?

This is OK in picipal. A typical parent child relation with object lifetime.
But you *must* not dereference the pointer (or reference) before the
contructor of B has completed. And also think about the case when B() or
one of it's subfunctions throws and A's destructor is called.

Marcel