Constructor chaining in C++

C++11 allows constructor chaining (partially). This feature is called “delegating constructors”. So in C++11 you can do the following

class Foo
{
public:
    Foo(int a) : Foo() { _a = a; }
    Foo(char* b) : Foo() { _b = b; }
    Foo() { _c = 1.5; }
private:
    int _a = 0;
    char* _b = nullptr;
    double _c;
};

However, there is a severe limitation that a constructor that calls another constructor is not allowed to initialize any other members. So you cannot do the following with a delegating constructor:

class Foo
{
public:
    Foo(int a) : Foo(), _a(a) { }
    Foo(char* b) : Foo(), _b(b) { }
    Foo() { _c = 1.5; }
private:
    int _a = 0;
    char* _b = nullptr;
    double _c;
};

MSVC++2013 gives compile error “C3511: a call to a delegating constructor shall be the only member-initializer” for the latter code example.