干净的 C++ 粒度朋友等价物?(答案:律师-客户成语)

I want to express interfaces with some routines to be invoked only by known callers without having to give those callers complete access to all privates, which feels like a reasonable thing to want. The best I could come up with myself (below) and suggestions by others so far revolve around idioms/pattern of varying indirectness, where I really just want a way to have single, simple class definitions that explicitly indicate what callers (more granularly than me, my children, or absolutely anybody) can access which members. What is the best way to express the concept below?

// Can I grant Y::usesX(...) selective X::restricted(...) access more cleanly?
void Y::usesX(int n, X *x, int m) {
  X::AttorneyY::restricted(*x, n);
}

struct X {
  class AttorneyY;          // Proxies restricted state to part or all of Y.
private:
  void restricted(int);     // Something preferably selectively available.
  friend class AttorneyY;   // Give trusted member class private access.
  int personal_;            // Truly private state ...
};

// Single abstract permission.  Can add more friends or forwards.
class X::AttorneyY {
  friend void Y::usesX(int, X *, int);
  inline static void restricted(X &x, int n) { x.restricted(n); }
};

我离成为一名软件组织大师还差得很远，但感觉界面简单性和最小权限原则在语言的这方面直接矛盾.我想要的一个更清晰的例子可能是一个 Person 类，其中声明了诸如 takePill(Medicine *) tellTheTruth() 和 forfeitDollars(unsigned int) 只有 Physician、Judge 或 TaxMan 实例/成员方法，分别应该考虑调用.每个主要接口方面都需要一次性代理或接口类让我感到不适，但如果您知道我遗漏了什么，请说出来.