Simplest way to initialize multiple related const properties in a constructor?

Question

When multiple const properties of a C++ class depend on some intermediate calculation, what is the simplest way to initialize them?

For example, how do I correct the constructor for the class below?

class MyClass {
public:
    const int a;
    const int b;

    MyClass() {
        int relatedVariable = rand() % 250;
        a = relatedVariable % 100;
        b = abs(relatedVariable - 150);
    }
};

Answer 1

This will kinda work for those of us who happen to prefer being less advanced in their coding:

class MyClass {
public:

    int iamStupid;      /* K.I.S.S. */

    const int a;
    const int b;

    MyClass()
      : iamStupid(rand() % 250)
      , a(iamStupid % 150)
      , b(abs(iamStupid - 150))
    {}
};

The additional member presents an unnecessary overhead — which may or may not be significant for the task at hand. OTOH, the code is simple.

Remember to declare iamStupid before a and b! (see comments)

Answer 2

Here's a roundabout solution using delegating constructors:

class MyClass
{
    MyClass(int aa, int bb) : a(aa), b(bb) { }

    static MyClass Maker() { int x = /* ... */; return MyClass(x * 2, x * 3); }

    int const a;
    int const b;

public:
    MyClass(MyClass const &) = default;
    MyClass() : MyClass(Maker()) { }
};