Avoid calling constructor of member variable

Question

I have the following C++-class:

// Header-File
class A
{
    public:
    A();

    private:
    B m_B;
    C m_C;
};

// cpp-File
A::A()
: m_B(1)
{
    m_B.doSom         


        

Answer 1

I don't see a good way to achieve what you want. This must be a workaround:

// Header-File
class A
{
    public:
    A();

    private:
    B m_B;
    C m_C;
    static int prepareC(B& b);
};

// cpp-File
A::A()
: m_B(1)
, m_C(prepareC(m_B))
{
}

int A::prepareC(B& b)
{
    b.doSomething();
    b.doMore();
    return b.getSomeValue();
}

Please ensure that m_B.doSomething(), m_B.doMore() and m_B.getSomeValue() don't touch m_C (directly or indirectly).

---

As @Tobias correctly mentions, this solution depends on the order of initialization. You need to ensure that the definitions of m_B and m_C are in this order.

---

Updated the code according to @Loki's idea.