Welk van de twee alternatieven hieronder is beter? Waarom?
(Noot: het gaat niet over de stijl.)

== Alternatief A
void
do_something() throw (std::runtime_error);

struct A {
  struct Lock {
    Lock(Dv::Thread::Monitor& m): m_(m) {
      m_.enter(); }
    ~Lock() { m_.exit(); }
    Dv::Thread::Monitor& m_;
  };
  void f() throw (std::runtime_error);
private:
  Dv::Thread::Monitor m_;
};

void 
A::f() throw (std::runtime_error) {
Lock l(m_);
do_something();
}

== Alternatief B
void
do_something() throw (std::runtime_error);

struct A {
  void f() throw (std::runtime_error);
private:
  Dv::Thread::Monitor m_;
};

void 
A::f() throw (std::runtime_error) {
m_.enter();
do_something();
m_.exit();
}