What is the best way to handle multiple object dependencies in C ++?

Question

I am building a C ++ application and I have several utility objects that all my classes should use. These are things like a logging object, a global state object, a DAL object, etc.

Until that moment, I passed all these objects as references to my class constructors.

For example:

class Honda: public Car
{
    public:
        Honda (const GlobalState & state, 
                const log & logger, 
                const DAL & dal);

    ...

    private:
      const GlobalState & my_state;
      const Log & my_logger;
      const DAL & my_dal;
}

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Answer 1

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Answer 2

GlobalState, Log, DAL:

class GlobalState {
public:
  static GlobalState& getInstance();
protected:
  GlobalState();
  GlobalState(const GlobalState&);
  GlobalState& operator= (const GlobalState&);
private:
  static GlobalState* p_instance;
};

static GlobalState* GlobalState::p_instance = NULL;

/*static*/
GlobalState& getInstance() {
  // TODO: acquire lock if multi-threaded
  if (!p_instance) {                 // first time?
    p_instance = new GlobalState(); // create sole instance
  }
  // TODO: release lock if multi-threaded
  return *p_instance;               // sole instance
}

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Honda::MyMethod() {
  ...
  const GlobalState& my_state = GlobalState::getInstance();
  ...
}

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Answer 3

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Answer 4

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GlobalState::getInstance()

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Answer 5

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Answer 6

: http://www.parashift.com/c++-faq-lite/ctors.html#faq-10.12

Answer 7

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