technique2.cpp

ThinkingC++中文版

//: C10:Technique2.cpp
// From Thinking in C++, 2nd Edition
// Available at http://www.BruceEckel.com
// (c) Bruce Eckel 2000
// Copyright notice in Copyright.txt
#include "Dependency2.h"
using namespace std;

// Returns a value so it can be called as
// a global initializer:
int separator() {
  cout << "---------------------" << endl;
  return 1;
}

// Simulate the dependency problem:
extern Dependency1 dep1;
Dependency2 dep2(dep1);
Dependency1 dep1;
int x1 = separator();

// But if it happens in this order it works OK:
Dependency1 dep1b;
Dependency2 dep2b(dep1b);
int x2 = separator();

// Wrapping static objects in functions succeeds
Dependency1& d1() {
  static Dependency1 dep1;
  return dep1;
}

Dependency2& d2() {
  static Dependency2 dep2(d1());
  return dep2;
}

int main() {
  Dependency2& dep2 = d2();
} ///:~