I’ve created an interface CanDo that defines one property someProperty. The interface is used to implement composition (classes implementing this interface should be used as parameter for doSomething()).

interface CanDo {
  someProperty;
}

function doSomething(arg: CanDo) {
 callOtherFunction(arg.someProperty);
}

class Class1 implements CanDo {
  someProperty;
}

class Class2 {
  someProperty;
}

const object1 = new Class1();
const object2 = new Class2();

doSomething(object1); //should work
doSomething(object2); //shouldn't work

The problem right now is that I can call doSomething() on both objects (since both define someProperty), but I only want it to be possible for objects of Class1.

How could I achieve this?