ctor_init_list_fallacy.cpp

#include <stdio.h>

class Component
{
public:
    int value;

    Component(int v) :
        value(v)
    {
        printf("Component(%d)\n", value);
    }
};

class Composite
{
public:
    Component a;
    Component b;

    /*
        Although the initializer list is written in the order: b, a, the member
        constructors will be executed in declaration order: a, b.
    */
    Composite() :
        b(1),
        a(b.value + 1)  // Counterintuitive: b.value is undefined at this line.
    { }
};

int main(int, char**)
{
    /*
        Here, one would expect the following output:

            > Component(1)
            > Component(2)

        But instead we will get:

            > Component(<random int value>)
            > Component(1)
    */
    Composite comp;

    return 0;
}