Contents

• Public Functions
• Detailed Description

Detailed Description

TheQ3Signal class can be used to send signals for classes that don't inheritQObject.

If you want to send signals from a class that does not inheritQObject, you can create an internalQ3Signal 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'sQMenuData class, which was not aQObject. In Qt 4, menus contain actions, which areQObjects.

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

You can set a singleQVariant parameter for the signal withsetValue().

Note thatQObject is aprivate base class ofQ3Signal, i.e. you cannot call anyQObject member functions from aQ3Signal object.

Example:

#include <q3signal.h>class MyClass{public:    MyClass();~MyClass();void doSomething();void connect(QObject*receiver,constchar*member);private:Q3Signal*sig;};MyClass::MyClass(){    sig=newQ3Signal;}MyClass::~MyClass(){delete sig;}void MyClass::doSomething(){// ... does something    sig->activate();// emits the signal}void MyClass::connect(QObject*receiver,constchar*member){    sig->connect(receiver, member);}

Member Function Documentation

Q3Signal::Q3Signal(QObject * parent = 0, constchar * name = 0)

Constructs a signal object calledname, with the parent objectparent. These arguments are passed directly toQObject.

Q3Signal::~Q3Signal()

Destroys the signal. All connections are removed, as is the case with allQObjects.

void Q3Signal::activate()

Emits the signal. If the platform supportsQVariant and a parameter has been set withsetValue(), this value is passed in the signal.

bool Q3Signal::connect(constQObject * receiver, constchar * member)

Connects the signal tomember in objectreceiver. Returns true if the connection is successful.

See alsodisconnect() andQObject::connect().

bool Q3Signal::disconnect(constQObject * receiver, constchar * member = 0)

Disonnects the signal frommember in objectreceiver. Returns true if the connection existed and the disconnect was successful.

See alsoconnect() andQObject::disconnect().

void Q3Signal::setValue(constQVariant & value)

Sets the signal's parameter tovalue

See alsovalue().

QVariant Q3Signal::value() const

Returns the signal's parameter

See alsosetValue().