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QSignal Class Reference

The QSignal class can be used to send signals without parameters. More...

#include <qsignal.h>

Inherits QObject.

List of all member functions.

Public Members


Detailed Description

The QSignal class can be used to send signals without parameters.

QSignal is a simple extension of QObject that can send plain signals without parameters. If you want to send signals from a class that does not inherit QObject, you can create an internal QSignal object to emit the signal. You must also provide a function that connects the signal to an outside object slot. This is how we have implemented signals in the QMenuData class, which is not a QObject.

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

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

Example:

    #include <qsignal.h>

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

        void doSomething();

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

    private:
        QSignal *sig;
    };

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

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

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

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

Member Function Documentation

QSignal::QSignal ( QObject * parent = 0, const char * name = 0 )

Constructs a signal object with the parent object parent and a name. These arguments are passed directly to QObject.

QSignal::~QSignal ()

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

void QSignal::activate ()

Emits the signal.

void QSignal::block ( bool b )

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

Blocks the signal if b is TRUE, or unblocks the signal if b is FALSE.

An activated signal disappears into hyperspace if it is blocked.

See also isBlocked(), activate() and QObject::blockSignals().

bool QSignal::connect ( const QObject * receiver, const char * member )

Connects the signal to member in object receiver.

See also disconnect() and QObject::connect().

bool QSignal::disconnect ( const QObject * receiver, const char * member = 0 )

Disonnects the signal from member in object receiver.

See also connect() and QObject::disconnect().

bool QSignal::isBlocked () const

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

Returns TRUE if the signal is blocked, or FALSE if it is not blocked.

The signal is not blocked by default.

See also block() and QObject::signalsBlocked().

int QSignal::parameter () const

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

void QSignal::setParameter ( int value )

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

void QSignal::setValue ( const QVariant & value )

Sets the signal's parameter to value

QVariant QSignal::value () const

Returns the signal's parameter

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