Q3Signal Class Reference

Detailed Description

The Q3Signal class can be used to send signals for classes that don't inherit QObject.

If you want to send signals from a class that does not inherit QObject, you can create an internal Q3Signal object to emit the signal. You must also provide a function that connects the signal to an outside object slot. This is how we used to implement signals in Qt 3's QMenuData class, which was not a QObject. In Qt 4, menus contain actions, which are QObjects.

In general, we recommend inheriting QObject instead. QObject provides much more functionality.

You can set a single QVariant parameter for the signal with setValue().

Note that QObject is a private base class of Q3Signal, i.e. you cannot call any QObject member functions from a Q3Signal object.

Example:

 #include <q3signal.h>

 class MyClass
 {
 public:
     MyClass();
     ~MyClass();

     void doSomething();

     void connect(QObject *receiver, const char *member);

 private:
     Q3Signal *sig;
 };

 MyClass::MyClass()
 {
     sig = new Q3Signal;
 }

 MyClass::~MyClass()
 {
     delete sig;
 }

 void MyClass::doSomething()
 {
     // ... does something
     sig->activate(); // emits the signal
 }

 void MyClass::connect(QObject *receiver, const char *member)
 {
     sig->connect(receiver, member);
 }