Signal 과 Slot 예제

<foo.h>

  #ifndef __FOO_H_
  #define __FOO_H_
  
  #include <QObject>
  
  class Foo : public QObject
  {
      Q_OBJECT
  
      public:
          Foo() {}
          int value() const { return val; }
  
          public slots:
              void setValue(int v)
              {
                  if(v != val)
                  {
                      val = v;
                      emit valueChanged(v);
                  }
              }
  
      signals:
          void valueChanged(int);
  
      private:
          int val;
  };
  
  #endif


<foo.cpp>        

  #include <QApplication>
  #include <iostream>
  
  using namespace std;
  
  #include "foo.h"
  
  int main(int argc, char ** argv)
  {
      QApplication app(argc, argv);
      Foo a,b;
      int ret;
  
      QObject::connect(&a, SIGNAL(valueChanged(int)), &b, SLOT(setValue(int)));
      b.setValue(11);
      a.setValue(79);
      ret = b.value();
  
      cout << ret << endl;
  
      return 0;
  }       

-> 출력 79