Private static variables to establish invariants

Question

Is it reasonable to use private static variables to establish invariants in your class?

Ex:

class MovingObject
{
public:
    //...Stuff
private:
    // Invariants
    static const double VELOCITY; // Moving objects always move at this velocity
    // etc. for any other invariants
    //...
}
---------------------------------------------------------------------------------
#include "MovingObject.h"
// Invariants
const double MovingObject::VELOCITY = 256.5;
//etc.

Answer 1

Yes, though those are generally called 'constants'. See the article anon linked for a discussion of 'invariant' as it's generally used in object-oriented design.

Answer 2

Sure. This is a common idiom across several OO languages including Java.