Редактирование: Qt:Документация 4.3.2/qobject

{{Qt4.3.2_header}}__NOTOC__

=QObject Class Reference<br /><sup><sup>[модуль [[Qt:Документация 4.3.2/qtcore | QtCore]] ] </sup></sup>=

The QObject class is the base class of all Qt objects. [[#details | More...]]

<source lang="cpp-qt"> #include <QObject></source> 
Inherited by [[Qt:Документация 4.3.2/q3accel | Q3Accel]], [[Qt:Документация 4.3.2/q3action | Q3Action]], [[Qt:Документация 4.3.2/q3canvas | Q3Canvas]], [[Qt:Документация 4.3.2/q3dns | Q3Dns]], [[Qt:Документация 4.3.2/q3dragobject | Q3DragObject]], [[Qt:Документация 4.3.2/q3editorfactory | Q3EditorFactory]], [[Qt:Документация 4.3.2/q3fileiconprovider | Q3FileIconProvider]], [[Qt:Документация 4.3.2/q3networkoperation | Q3NetworkOperation]], [[Qt:Документация 4.3.2/q3networkprotocol | Q3NetworkProtocol]], [[Qt:Документация 4.3.2/q3process | Q3Process]], [[Qt:Документация 4.3.2/q3serversocket | Q3ServerSocket]], [[Qt:Документация 4.3.2/q3signal | Q3Signal]], [[Qt:Документация 4.3.2/q3sqlform | Q3SqlForm]], [[Qt:Документация 4.3.2/q3stylesheet | Q3StyleSheet]], [[Qt:Документация 4.3.2/q3urloperator | Q3UrlOperator]], [[Qt:Документация 4.3.2/q3whatsthis | Q3WhatsThis]], [[Qt:Документация 4.3.2/qabstracteventdispatcher | QAbstractEventDispatcher]], [[Qt:Документация 4.3.2/qabstractfontengine | QAbstractFontEngine]], [[Qt:Документация 4.3.2/qabstractitemdelegate | QAbstractItemDelegate]], [[Qt:Документация 4.3.2/qabstractitemmodel | QAbstractItemModel]], [[Qt:Документация 4.3.2/qabstracttextdocumentlayout | QAbstractTextDocumentLayout]], [[Qt:Документация 4.3.2/qaccessiblebridgeplugin | QAccessibleBridgePlugin]], [[Qt:Документация 4.3.2/qaccessibleplugin | QAccessiblePlugin]], [[Qt:Документация 4.3.2/qaction | QAction]], [[Qt:Документация 4.3.2/qactiongroup | QActionGroup]], [[Qt:Документация 4.3.2/qassistantclient | QAssistantClient]], [[Qt:Документация 4.3.2/qaxfactory | QAxFactory]], [[Qt:Документация 4.3.2/qaxobject | QAxObject]], [[Qt:Документация 4.3.2/qaxscript | QAxScript]], [[Qt:Документация 4.3.2/qaxscriptmanager | QAxScriptManager]], [[Qt:Документация 4.3.2/qbuttongroup | QButtonGroup]], [[Qt:Документация 4.3.2/qclipboard | QClipboard]], [[Qt:Документация 4.3.2/qcompleter | QCompleter]], [[Qt:Документация 4.3.2/qcopchannel | QCopChannel]], [[Qt:Документация 4.3.2/qcoreapplication | QCoreApplication]], [[Qt:Документация 4.3.2/qdatawidgetmapper | QDataWidgetMapper]], [[Qt:Документация 4.3.2/qdbusabstractadaptor | QDBusAbstractAdaptor]], [[Qt:Документация 4.3.2/qdbusabstractinterface | QDBusAbstractInterface]], [[Qt:Документация 4.3.2/qdbusserver | QDBusServer]], [[Qt:Документация 4.3.2/qdecorationplugin | QDecorationPlugin]], [[Qt:Документация 4.3.2/qdesignerformeditorinterface | QDesignerFormEditorInterface]], [[Qt:Документация 4.3.2/qdesignerformwindowmanagerinterface | QDesignerFormWindowManagerInterface]], [[Qt:Документация 4.3.2/qdirectpainter | QDirectPainter]], [[Qt:Документация 4.3.2/qdrag | QDrag]], [[Qt:Документация 4.3.2/qeventloop | QEventLoop]], [[Qt:Документация 4.3.2/qextensionfactory | QExtensionFactory]], [[Qt:Документация 4.3.2/qextensionmanager | QExtensionManager]], [[Qt:Документация 4.3.2/qfilesystemwatcher | QFileSystemWatcher]], [[Qt:Документация 4.3.2/qfontengineplugin | QFontEnginePlugin]], [[Qt:Документация 4.3.2/qftp | QFtp]], [[Qt:Документация 4.3.2/qgraphicsitemanimation | QGraphicsItemAnimation]], [[Qt:Документация 4.3.2/qgraphicsscene | QGraphicsScene]], [[Qt:Документация 4.3.2/qgraphicssvgitem | QGraphicsSvgItem]], [[Qt:Документация 4.3.2/qgraphicstextitem | QGraphicsTextItem]], [[Qt:Документация 4.3.2/qhttp | QHttp]], [[Qt:Документация 4.3.2/qiconengineplugin | QIconEnginePlugin]], [[Qt:Документация 4.3.2/qiconenginepluginv2 | QIconEnginePluginV2]], [[Qt:Документация 4.3.2/qimageioplugin | QImageIOPlugin]], [[Qt:Документация 4.3.2/qinputcontext | QInputContext]], [[Qt:Документация 4.3.2/qinputcontextplugin | QInputContextPlugin]], [[Qt:Документация 4.3.2/qiodevice | QIODevice]], [[Qt:Документация 4.3.2/qitemselectionmodel | QItemSelectionModel]], [[Qt:Документация 4.3.2/qkbddriverplugin | QKbdDriverPlugin]], [[Qt:Документация 4.3.2/qlayout | QLayout]], [[Qt:Документация 4.3.2/qlibrary | QLibrary]], [[Qt:Документация 4.3.2/qmimedata | QMimeData]], [[Qt:Документация 4.3.2/qmousedriverplugin | QMouseDriverPlugin]], [[Qt:Документация 4.3.2/qmovie | QMovie]], [[Qt:Документация 4.3.2/qobjectcleanuphandler | QObjectCleanupHandler]], [[Qt:Документация 4.3.2/qpictureformatplugin | QPictureFormatPlugin]], [[Qt:Документация 4.3.2/qpluginloader | QPluginLoader]], [[Qt:Документация 4.3.2/qscreendriverplugin | QScreenDriverPlugin]], [[Qt:Документация 4.3.2/qscript-connectionqobject | QScript::ConnectionQObject]], [[Qt:Документация 4.3.2/qscriptengine | QScriptEngine]], [[Qt:Документация 4.3.2/qscriptextensionplugin | QScriptExtensionPlugin]], [[Qt:Документация 4.3.2/qsessionmanager | QSessionManager]], [[Qt:Документация 4.3.2/qsettings | QSettings]], [[Qt:Документация 4.3.2/qshortcut | QShortcut]], [[Qt:Документация 4.3.2/qsignalmapper | QSignalMapper]], [[Qt:Документация 4.3.2/qsignalspy | QSignalSpy]], [[Qt:Документация 4.3.2/qsocketnotifier | QSocketNotifier]], [[Qt:Документация 4.3.2/qsound | QSound]], [[Qt:Документация 4.3.2/qsqldriver | QSqlDriver]], [[Qt:Документация 4.3.2/qsqldriverplugin | QSqlDriverPlugin]], [[Qt:Документация 4.3.2/qstyle | QStyle]], [[Qt:Документация 4.3.2/qstyleplugin | QStylePlugin]], [[Qt:Документация 4.3.2/qsvgrenderer | QSvgRenderer]], [[Qt:Документация 4.3.2/qsyntaxhighlighter | QSyntaxHighlighter]], [[Qt:Документация 4.3.2/qsystemtrayicon | QSystemTrayIcon]], [[Qt:Документация 4.3.2/qtcpserver | QTcpServer]], [[Qt:Документация 4.3.2/qtextcodecplugin | QTextCodecPlugin]], [[Qt:Документация 4.3.2/qtextdocument | QTextDocument]], [[Qt:Документация 4.3.2/qtextobject | QTextObject]], [[Qt:Документация 4.3.2/qthread | QThread]], [[Qt:Документация 4.3.2/qtimeline | QTimeLine]], [[Qt:Документация 4.3.2/qtimer | QTimer]], [[Qt:Документация 4.3.2/qtranslator | QTranslator]], [[Qt:Документация 4.3.2/quiloader | QUiLoader]], [[Qt:Документация 4.3.2/qundogroup | QUndoGroup]], [[Qt:Документация 4.3.2/qundostack | QUndoStack]], [[Qt:Документация 4.3.2/qvalidator | QValidator]], [[Qt:Документация 4.3.2/qwidget | QWidget]], [[Qt:Документация 4.3.2/qwsclient | QWSClient]], [[Qt:Документация 4.3.2/qwsinputmethod | QWSInputMethod]], and [[Qt:Документация 4.3.2/qwsserver | QWSServer]].

'''Note:''' All the functions in this class are [[Qt:Документация 4.3.2/threads#reentrant | reentrant]], except [[Qt:Документация 4.3.2/qobject#installEventFilter | installEventFilter]](), [[Qt:Документация 4.3.2/qobject#removeEventFilter | removeEventFilter]](), [[Qt:Документация 4.3.2/qobject#connect | connect]](), [[Qt:Документация 4.3.2/qobject#connect-2 | connect]](), [[Qt:Документация 4.3.2/qobject#disconnect | disconnect]](), and [[Qt:Документация 4.3.2/qobject#disconnect-2 | disconnect]]().

*[[Qt:Документация 4.3.2/qobject-members | Список всех членов включая унаследованные]]
*[[Qt:Документация 4.3.2/qobject-qt3 | Поддержка членов Qt 3]]
<div id="properties"></div>
===Свойства===

*'''[[Qt:Документация 4.3.2/qobject#objectName-prop | objectName]]''' : QString
<div id="public-functions"></div>
===Открытые функции===

*'''[[Qt:Документация 4.3.2/qobject#QObject | QObject]]''' ( QObject * ''parent'' = 0 )
*virtual '''[[Qt:Документация 4.3.2/qobject#dtor.QObject | ~QObject]]''' ()
*bool '''[[Qt:Документация 4.3.2/qobject#blockSignals | blockSignals]]''' ( bool ''block'' )
*const QObjectList &amp; '''[[Qt:Документация 4.3.2/qobject#children | children]]''' () const
*bool '''[[Qt:Документация 4.3.2/qobject#connect-2 | connect]]''' ( const QObject * ''sender'', const char * ''signal'', const char * ''method'', Qt::ConnectionType ''type'' = Qt::AutoCompatConnection ) const
*bool '''[[Qt:Документация 4.3.2/qobject#disconnect-2 | disconnect]]''' ( const char * ''signal'' = 0, const QObject * ''receiver'' = 0, const char * ''method'' = 0 )
*bool '''[[Qt:Документация 4.3.2/qobject#disconnect-3 | disconnect]]''' ( const QObject * ''receiver'', const char * ''method'' = 0 )
*void '''[[Qt:Документация 4.3.2/qobject#dumpObjectInfo | dumpObjectInfo]]''' ()
*void '''[[Qt:Документация 4.3.2/qobject#dumpObjectTree | dumpObjectTree]]''' ()
*QList<QByteArray> '''[[Qt:Документация 4.3.2/qobject#dynamicPropertyNames | dynamicPropertyNames]]''' () const
*virtual bool '''[[Qt:Документация 4.3.2/qobject#event | event]]''' ( QEvent * ''e'' )
*virtual bool '''[[Qt:Документация 4.3.2/qobject#eventFilter | eventFilter]]''' ( QObject * ''watched'', QEvent * ''event'' )
*T '''[[Qt:Документация 4.3.2/qobject#findChild | findChild]]''' ( const QString &amp; ''name'' = QString() ) const
*QList<T> '''[[Qt:Документация 4.3.2/qobject#findChildren | findChildren]]''' ( const QString &amp; ''name'' = QString() ) const
*QList<T> '''[[Qt:Документация 4.3.2/qobject#findChildren-2 | findChildren]]''' ( const QRegExp &amp; ''regExp'' ) const
*bool '''[[Qt:Документация 4.3.2/qobject#inherits | inherits]]''' ( const char * ''className'' ) const
*void '''[[Qt:Документация 4.3.2/qobject#installEventFilter | installEventFilter]]''' ( QObject * ''filterObj'' )
*bool '''[[Qt:Документация 4.3.2/qobject#isWidgetType | isWidgetType]]''' () const
*void '''[[Qt:Документация 4.3.2/qobject#killTimer | killTimer]]''' ( int ''id'' )
*virtual const QMetaObject * '''[[Qt:Документация 4.3.2/qobject#metaObject | metaObject]]''' () const
*void '''[[Qt:Документация 4.3.2/qobject#moveToThread | moveToThread]]''' ( QThread * ''targetThread'' )
*QString '''[[Qt:Документация 4.3.2/qobject#objectName-prop | objectName]]''' () const
*QObject * '''[[Qt:Документация 4.3.2/qobject#parent | parent]]''' () const
*QVariant '''[[Qt:Документация 4.3.2/qobject#property | property]]''' ( const char * ''name'' ) const
*void '''[[Qt:Документация 4.3.2/qobject#removeEventFilter | removeEventFilter]]''' ( QObject * ''obj'' )
*void '''[[Qt:Документация 4.3.2/qobject#objectName-prop | setObjectName]]''' ( const QString &amp; ''name'' )
*void '''[[Qt:Документация 4.3.2/qobject#setParent | setParent]]''' ( QObject * ''parent'' )
*bool '''[[Qt:Документация 4.3.2/qobject#setProperty | setProperty]]''' ( const char * ''name'', const QVariant &amp; ''value'' )
*bool '''[[Qt:Документация 4.3.2/qobject#signalsBlocked | signalsBlocked]]''' () const
*int '''[[Qt:Документация 4.3.2/qobject#startTimer | startTimer]]''' ( int ''interval'' )
*QThread * '''[[Qt:Документация 4.3.2/qobject#thread | thread]]''' () const
<div id="public-slots"></div>
===Открытые слоты===

*void '''[[Qt:Документация 4.3.2/qobject#deleteLater | deleteLater]]''' ()
<div id="signals"></div>
===Сигналы===

*void '''[[Qt:Документация 4.3.2/qobject#destroyed | destroyed]]''' ( QObject * ''obj'' = 0 )
<div id="static-public-members"></div>
===Статические открытые члены===

*bool '''[[Qt:Документация 4.3.2/qobject#connect | connect]]''' ( const QObject * ''sender'', const char * ''signal'', const QObject * ''receiver'', const char * ''method'', Qt::ConnectionType ''type'' = Qt::AutoCompatConnection )
*bool '''[[Qt:Документация 4.3.2/qobject#disconnect | disconnect]]''' ( const QObject * ''sender'', const char * ''signal'', const QObject * ''receiver'', const char * ''method'' )
*const QMetaObject '''[[Qt:Документация 4.3.2/qobject#staticMetaObject-var | staticMetaObject]]'''
*QString '''[[Qt:Документация 4.3.2/qobject#tr | tr]]''' ( const char * ''sourceText'', const char * ''comment'' = 0, int ''n'' = -1 )
*QString '''[[Qt:Документация 4.3.2/qobject#trUtf8 | trUtf8]]''' ( const char * ''sourceText'', const char * ''comment'' = 0, int ''n'' = -1 )
<div id="protected-functions"></div>
===Защищенные функции===

*virtual void '''[[Qt:Документация 4.3.2/qobject#childEvent | childEvent]]''' ( QChildEvent * ''event'' )
*virtual void '''[[Qt:Документация 4.3.2/qobject#connectNotify | connectNotify]]''' ( const char * ''signal'' )
*virtual void '''[[Qt:Документация 4.3.2/qobject#customEvent | customEvent]]''' ( QEvent * ''event'' )
*virtual void '''[[Qt:Документация 4.3.2/qobject#disconnectNotify | disconnectNotify]]''' ( const char * ''signal'' )
*int '''[[Qt:Документация 4.3.2/qobject#receivers | receivers]]''' ( const char * ''signal'' ) const
*QObject * '''[[Qt:Документация 4.3.2/qobject#sender | sender]]''' () const
*virtual void '''[[Qt:Документация 4.3.2/qobject#timerEvent | timerEvent]]''' ( QTimerEvent * ''event'' )
<div id="related-non-members"></div>
===Связанные не-члены===

*typedef '''[[Qt:Документация 4.3.2/qobject#QObjectList-typedef | QObjectList]]'''
*T '''[[Qt:Документация 4.3.2/qobject#qFindChild | qFindChild]]''' ( const QObject * ''obj'', const QString &amp; ''name'' )
*QList<T> '''[[Qt:Документация 4.3.2/qobject#qFindChildren | qFindChildren]]''' ( const QObject * ''obj'', const QString &amp; ''name'' )
*QList<T> '''[[Qt:Документация 4.3.2/qobject#qFindChildren-6 | qFindChildren]]''' ( const QObject * ''obj'', const QRegExp &amp; ''regExp'' )
*T '''[[Qt:Документация 4.3.2/qobject#qobject_cast | qobject_cast]]''' ( QObject * ''object'' )
<div id="macros"></div>
===Макросы===

*'''[[Qt:Документация 4.3.2/qobject#Q_CLASSINFO | Q_CLASSINFO]]''' (  ''Name'',  ''Value'' )
*'''[[Qt:Документация 4.3.2/qobject#Q_ENUMS | Q_ENUMS]]''' ( ... )
*'''[[Qt:Документация 4.3.2/qobject#Q_FLAGS | Q_FLAGS]]''' ( ... )
*'''[[Qt:Документация 4.3.2/qobject#Q_INTERFACES | Q_INTERFACES]]''' ( ... )
*'''[[Qt:Документация 4.3.2/qobject#Q_OBJECT | Q_OBJECT]]'''
*'''[[Qt:Документация 4.3.2/qobject#Q_PROPERTY | Q_PROPERTY]]''' ( ... )
<div id="details"></div><hr />
==Подробное описание==

The QObject class is the base class of all Qt objects.

QObject is the heart of the [[Qt:Документация 4.3.2/object | Qt object model]]. The central feature in this model is a very powerful mechanism for seamless object communication called [[Qt:Документация 4.3.2/signalsandslots | signals and slots]]. You can connect a signal to a slot with [[Qt:Документация 4.3.2/qobject#connect | connect]]() and destroy the connection with [[Qt:Документация 4.3.2/qobject#disconnect | disconnect]](). To avoid never ending notification loops you can temporarily block signals with [[Qt:Документация 4.3.2/qobject#blockSignals | blockSignals]](). The protected functions [[Qt:Документация 4.3.2/qobject#connectNotify | connectNotify]]() and [[Qt:Документация 4.3.2/qobject#disconnectNotify | disconnectNotify]]() make it possible to track connections.

QObjects organize themselves in object trees. When you create a QObject with another object as parent, the object will automatically add itself to the parent's [[Qt:Документация 4.3.2/qobject#children | children]]() list. The parent takes ownership of the object i.e&#x2e; it will automatically delete its children in its destructor. You can look for an object by name and optionally type using [[Qt:Документация 4.3.2/qobject#findChild | findChild]]() or [[Qt:Документация 4.3.2/qobject#findChildren | findChildren]]().

Every object has an [[Qt:Документация 4.3.2/qobject#objectName-prop | objectName]]() and its class name can be found via the corresponding [[Qt:Документация 4.3.2/qobject#metaObject | metaObject]]() (see [[Qt:Документация 4.3.2/qmetaobject#className | QMetaObject::className]]()). You can determine whether the object's class inherits another class in the QObject inheritance hierarchy by using the [[Qt:Документация 4.3.2/qobject#inherits | inherits]]() function.

When an object is deleted, it emits a [[Qt:Документация 4.3.2/qobject#destroyed | destroyed]]() signal. You can catch this signal to avoid dangling references to QObjects.

QObjects can receive events through [[Qt:Документация 4.3.2/qobject#event | event]]() and filter the events of other objects. See [[Qt:Документация 4.3.2/qobject#installEventFilter | installEventFilter]]() and [[Qt:Документация 4.3.2/qobject#eventFilter | eventFilter]]() for details. A convenience handler, [[Qt:Документация 4.3.2/qobject#childEvent | childEvent]](), can be reimplemented to catch child events.

Events are delivered in the thread in which the object was created; see [[Qt:Документация 4.3.2/threads | Thread Support in Qt]] and [[Qt:Документация 4.3.2/qobject#thread | thread]]() for details. Note that event processing is not done at all for QObjects with no thread affinity ([[Qt:Документация 4.3.2/qobject#thread | thread]]() returns zero). Use the [[Qt:Документация 4.3.2/qobject#moveToThread | moveToThread]]() function to change the thread affinity for an object and its children (the object cannot be moved if it has a parent).

Last but not least, QObject provides the basic timer support in Qt; see [[Qt:Документация 4.3.2/qtimer | QTimer]] for high-level support for timers.

Notice that the [[Qt:Документация 4.3.2/qobject#Q_OBJECT | Q_OBJECT]] macro is mandatory for any object that implements signals, slots or properties. You also need to run the [[Qt:Документация 4.3.2/moc#moc | Meta Object Compiler]] on the source file. We strongly recommend the use of this macro in all subclasses of QObject regardless of whether or not they actually use signals, slots and properties, since failure to do so may lead certain functions to exhibit strange behavior.

All Qt widgets inherit QObject. The convenience function [[Qt:Документация 4.3.2/qobject#isWidgetType | isWidgetType]]() returns whether an object is actually a widget. It is much faster than [[Qt:Документация 4.3.2/qobject#qobject_cast | qobject_cast]]<[[Qt:Документация 4.3.2/qwidget | QWidget]] *>(''obj'') or ''obj''->[[Qt:Документация 4.3.2/qobject#inherits | inherits]]("[[Qt:Документация 4.3.2/qwidget | QWidget]]").

Some QObject functions, e.g&#x2e; [[Qt:Документация 4.3.2/qobject#children | children]](), return a [[Qt:Документация 4.3.2/qobject#QObjectList-typedef | QObjectList]]. [[Qt:Документация 4.3.2/qobject#QObjectList-typedef | QObjectList]] is a typedef for [[Qt:Документация 4.3.2/qlist | QList]]<QObject *>.
<div id="auto-connection"></div>
===Auto-Connection===

Qt's meta-object system provides a mechanism to automatically connect signals and slots between QObject subclasses and their children. As long as objects are defined with suitable object names, and slots follow a simple naming convention, this connection can be performed at run-time by the [[Qt:Документация 4.3.2/qmetaobject#connectSlotsByName | QMetaObject::connectSlotsByName]]() function.

[[Qt:Документация 4.3.2/uic#uic | uic]] generates code that invokes this function to enable auto-connection to be performed between widgets on forms created with ''Qt Designer''. More information about using auto-connection with ''Qt Designer'' is given in the [[Qt:Документация 4.3.2/designer-using-a-component | Using a Component in Your Application]] section of the ''Qt Designer'' manual.
<div id="dynamic-properties"></div>
===Dynamic Свойства===

From Qt 4.2, dynamic properties can be added to and removed from QObject instances at run-time. Dynamic properties do not need to be declared at compile-time, yet they provide the same advantages as static properties and are manipulated using the same API - using [[Qt:Документация 4.3.2/qobject#property | property]]() to read them and [[Qt:Документация 4.3.2/qobject#setProperty | setProperty]]() to write them.

From Qt 4.3, dynamic properties are supported by [[Qt:Документация 4.3.2/designer-editing-mode#the-property-editor | Qt Designer]], and both standard Qt widgets and user-created forms can be given dynamic properties.

See also [[Qt:Документация 4.3.2/qmetaobject | QMetaObject]], [[Qt:Документация 4.3.2/qpointer | QPointer]], [[Qt:Документация 4.3.2/qobjectcleanuphandler | QObjectCleanupHandler]], and [[Qt:Документация 4.3.2/objecttrees | Object Trees and Object Ownership]].
<hr />
==Описание свойств==

===<div id="objectName-prop"></div>objectName : [[Qt:Документация 4.3.2/qstring | QString]]===

This property holds the name of this object.

You can find an object by name (and type) using [[Qt:Документация 4.3.2/qobject#findChild | findChild]](). You can find a set of objects with [[Qt:Документация 4.3.2/qobject#findChildren | findChildren]]().
<source lang="cpp-qt"> qDebug("MyClass::setPrecision(): (%s) invalid precision %f",
        qPrintable(objectName()), newPrecision);</source> 
Функции доступа:

*'''QString objectName () const'''
*'''void setObjectName ( const QString &amp; ''name'' )'''

See also [[Qt:Документация 4.3.2/qobject#metaObject | metaObject]]() and [[Qt:Документация 4.3.2/qmetaobject#className | QMetaObject::className]]().
<hr />
==Описание функций-членов==

===<div id="QObject"></div>QObject::QObject ( QObject * ''parent'' = 0 )===

Constructs an object with parent object ''parent''.

The parent of an object may be viewed as the object's owner. For instance, a [[Qt:Документация 4.3.2/qdialog | dialog box]] is the parent of the '''OK''' and '''Cancel''' buttons it contains.

The destructor of a parent object destroys all child objects.

Setting ''parent'' to 0 constructs an object with no parent. If the object is a widget, it will become a top-level window.

See also [[Qt:Документация 4.3.2/qobject#parent | parent]](), [[Qt:Документация 4.3.2/qobject#findChild | findChild]](), and [[Qt:Документация 4.3.2/qobject#findChildren | findChildren]]().

===<div id="dtor.QObject"></div>QObject::~QObject ()  <tt> [virtual]</tt>===

Destroys the object, deleting all its child objects.

All signals to and from the object are automatically disconnected, and any pending posted events for the object are removed from the event queue. However, it is often safer to use [[Qt:Документация 4.3.2/qobject#deleteLater | deleteLater]]() rather than deleting a [[Qt:Документация 4.3.2/qobject | QObject]] subclass directly.

'''Warning:''' All child objects are deleted. If any of these objects are on the stack or global, sooner or later your program will crash. We do not recommend holding pointers to child objects from outside the parent. If you still do, the [[Qt:Документация 4.3.2/qobject#destroyed | destroyed]]() signal gives you an opportunity to detect when an object is destroyed.

'''Warning:''' Deleting a [[Qt:Документация 4.3.2/qobject | QObject]] while pending events are waiting to be delivered can cause a crash. You must not delete the [[Qt:Документация 4.3.2/qobject | QObject]] directly if it exists in a different thread than the one currently executing. Use [[Qt:Документация 4.3.2/qobject#deleteLater | deleteLater]]() instead, which will cause the event loop to delete the object after all pending events have been delivered to it.

See also [[Qt:Документация 4.3.2/qobject#deleteLater | deleteLater]]().

===<div id="blockSignals"></div>bool QObject::blockSignals ( bool ''block'' )===

If ''block'' is true, signals emitted by this object are blocked (i.e&#x2e;, emitted signals disappear into hyperspace). If ''block'' is false, no such blocking will occur.

The return value is the previous value of [[Qt:Документация 4.3.2/qobject#signalsBlocked | signalsBlocked]]().

Note that the [[Qt:Документация 4.3.2/qobject#destroyed | destroyed]]() signal will be emitted even if the signals for this object have been blocked.

See also [[Qt:Документация 4.3.2/qobject#signalsBlocked | signalsBlocked]]().

===<div id="childEvent"></div>void QObject::childEvent ( [[Qt:Документация 4.3.2/qchildevent | QChildEvent]] * ''event'' )  <tt> [virtual protected]</tt>===

This event handler can be reimplemented in a subclass to receive child events. The event is passed in the ''event'' parameter.

[[Qt:Документация 4.3.2/qevent#Type-enum | QEvent::ChildAdded]] and [[Qt:Документация 4.3.2/qevent#Type-enum | QEvent::ChildRemoved]] events are sent to objects when children are added or removed. In both cases you can only rely on the child being a [[Qt:Документация 4.3.2/qobject | QObject]], or if [[Qt:Документация 4.3.2/qobject#isWidgetType | isWidgetType]]() returns true, a [[Qt:Документация 4.3.2/qwidget | QWidget]]. (This is because, in the [[Qt:Документация 4.3.2/qevent#Type-enum | ChildAdded]] case, the child is not yet fully constructed, and in the [[Qt:Документация 4.3.2/qevent#Type-enum | ChildRemoved]] case it might have been destructed already).

[[Qt:Документация 4.3.2/qevent#Type-enum | QEvent::ChildPolished]] events are sent to widgets when children are polished, or when polished children are added. If you receive a child polished event, the child's construction is usually completed.

For every child widget, you receive one [[Qt:Документация 4.3.2/qevent#Type-enum | ChildAdded]] event, zero or more [[Qt:Документация 4.3.2/qevent#Type-enum | ChildPolished]] events, and one [[Qt:Документация 4.3.2/qevent#Type-enum | ChildRemoved]] event.

The [[Qt:Документация 4.3.2/qevent#Type-enum | ChildPolished]] event is omitted if a child is removed immediately after it is added. If a child is polished several times during construction and destruction, you may receive several child polished events for the same child, each time with a different virtual table.

See also [[Qt:Документация 4.3.2/qobject#event | event]]().

===<div id="children"></div>const [[Qt:Документация 4.3.2/qobject#QObjectList-typedef | QObjectList]] &amp; QObject::children () const===

Returns a list of child objects. The [[Qt:Документация 4.3.2/qobject#QObjectList-typedef | QObjectList]] class is defined in the <tt><QObject></tt> header file as the following:
<source lang="cpp-qt"> typedef QList<QObject*> QObjectList;</source> 
The first child added is the [[Qt:Документация 4.3.2/qlist#first | first]] object in the list and the last child added is the [[Qt:Документация 4.3.2/qlist#last | last]] object in the list, i.e&#x2e; new children are appended at the end.

Note that the list order changes when [[Qt:Документация 4.3.2/qwidget | QWidget]] children are [[Qt:Документация 4.3.2/qwidget#raise | raised]] or [[Qt:Документация 4.3.2/qwidget#lower | lowered]]. A widget that is raised becomes the last object in the list, and a widget that is lowered becomes the first object in the list.

See also [[Qt:Документация 4.3.2/qobject#findChild | findChild]](), [[Qt:Документация 4.3.2/qobject#findChildren | findChildren]](), [[Qt:Документация 4.3.2/qobject#parent | parent]](), and [[Qt:Документация 4.3.2/qobject#setParent | setParent]]().

===<div id="connect"></div>bool QObject::connect ( const QObject * ''sender'', const char * ''signal'', const QObject * ''receiver'', const char * ''method'', [[Qt:Документация 4.3.2/qt#ConnectionType-enum | Qt::ConnectionType]] ''type'' = Qt::AutoCompatConnection )  <tt> [static]</tt>===

Creates a connection of the given ''type'' from the ''signal'' in the ''sender'' object to the ''method'' in the ''receiver'' object. Returns true if the connection succeeds; otherwise returns false.

You must use the <tt>SIGNAL()</tt> and <tt>SLOT()</tt> macros when specifying the ''signal'' and the ''method'', for example:
<source lang="cpp-qt"> QLabel *label = new QLabel;
 QScrollBar *scrollBar = new QScrollBar;
 QObject::connect(scrollBar, SIGNAL(valueChanged(int)),
                  label,  SLOT(setNum(int)));</source> 
This example ensures that the label always displays the current scroll bar value. Note that the signal and slots parameters must not contain any variable names, only the type. E.g&#x2e; the following would not work and return false:
<source lang="cpp-qt"> // WRONG
 QObject::connect(scrollBar, SIGNAL(valueChanged(int value)),
                  label, SLOT(setNum(int value)));</source> 
A signal can also be connected to another signal:
<source lang="cpp-qt"> class MyWidget : public QWidget
 {
     Q_OBJECT

 public:
     MyWidget();

 signals:
     void buttonClicked();

 private:
     QPushButton *myButton;
 };

 MyWidget::MyWidget()
 {
     myButton = new QPushButton(this);
     connect(myButton, SIGNAL(clicked()),
             this, SIGNAL(buttonClicked()));
 }</source> 
In this example, the <tt>MyWidget</tt> constructor relays a signal from a private member variable, and makes it available under a name that relates to <tt>MyWidget</tt>.

A signal can be connected to many slots and signals. Many signals can be connected to one slot.

If a signal is connected to several slots, the slots are activated in an arbitrary order when the signal is emitted.

The function returns true if it successfully connects the signal to the slot. It will return false if it cannot create the connection, for example, if [[Qt:Документация 4.3.2/qobject | QObject]] is unable to verify the existence of either ''signal'' or ''method'', or if their signatures aren't compatible.

A signal is emitted for every connection you make, so if you duplicate a connection, two signals will be emitted. You can always break a connection using [[Qt:Документация 4.3.2/qobject#disconnect | disconnect]]().

The optional ''type'' parameter describes the type of connection to establish. In particular, it determines whether a particular signal is delivered to a slot immediately or queued for delivery at a later time. If the signal is queued, the parameters must be of types that are known to Qt's meta-object system, because Qt needs to copy the arguments to store them in an event behind the scenes. If you try to use a queued connection and get the error message
<source lang="cpp-qt"> QObject::connect: Cannot queue arguments of type 'MyType'
 (Make sure 'MyType' is registered using qRegisterMetaType().)</source> 
call [[Qt:Документация 4.3.2/qmetatype#qRegisterMetaType | qRegisterMetaType]]() to register the data type before you establish the connection.

'''Note:''' This function is [[Qt:Документация 4.3.2/threads#thread-safe | thread-safe]].

See also [[Qt:Документация 4.3.2/qobject#disconnect | disconnect]](), [[Qt:Документация 4.3.2/qobject#sender | sender]](), and [[Qt:Документация 4.3.2/qmetatype#qRegisterMetaType | qRegisterMetaType]]().

===<div id="connect-2"></div>bool QObject::connect ( const QObject * ''sender'', const char * ''signal'', const char * ''method'', [[Qt:Документация 4.3.2/qt#ConnectionType-enum | Qt::ConnectionType]] ''type'' = Qt::AutoCompatConnection ) const===

This is an overloaded member function, provided for convenience.

Connects ''signal'' from the ''sender'' object to this object's ''method''.

Equivalent to connect(''sender'', ''signal'', <tt>this</tt>, ''method'', ''type'').

Every connection you make emits a signal, so duplicate connections emit two signals. You can break a connection using [[Qt:Документация 4.3.2/qobject#disconnect | disconnect]]().

'''Note:''' This function is [[Qt:Документация 4.3.2/threads#thread-safe | thread-safe]].

See also [[Qt:Документация 4.3.2/qobject#disconnect | disconnect]]().

===<div id="connectNotify"></div>void QObject::connectNotify ( const char * ''signal'' )  <tt> [virtual protected]</tt>===

This virtual function is called when something has been connected to ''signal'' in this object.

If you want to compare ''signal'' with a specific signal, use [[Qt:Документация 4.3.2/qlatin1string | QLatin1String]] and the <tt>SIGNAL()</tt> macro as follows:
<source lang="cpp-qt"> if (QLatin1String(signal) == SIGNAL(valueChanged(int))) {
     // signal is valueChanged(int)
 }</source> 
If the signal contains multiple parameters or parameters that contain spaces, call [[Qt:Документация 4.3.2/qmetaobject#normalizedSignature | QMetaObject::normalizedSignature]]() on the result of the <tt>SIGNAL()</tt> macro.

'''Warning:''' This function violates the object-oriented principle of modularity. However, it might be useful when you need to perform expensive initialization only if something is connected to a signal.

See also [[Qt:Документация 4.3.2/qobject#connect | connect]]() and [[Qt:Документация 4.3.2/qobject#disconnectNotify | disconnectNotify]]().

===<div id="customEvent"></div>void QObject::customEvent ( [[Qt:Документация 4.3.2/qevent | QEvent]] * ''event'' )  <tt> [virtual protected]</tt>===

This event handler can be reimplemented in a subclass to receive custom events. Custom events are user-defined events with a type value at least as large as the [[Qt:Документация 4.3.2/qevent#Type-enum | QEvent::User]] item of the [[Qt:Документация 4.3.2/qevent#Type-enum | QEvent::Type]] enum, and is typically a [[Qt:Документация 4.3.2/qevent | QEvent]] subclass. The event is passed in the ''event'' parameter.

See also [[Qt:Документация 4.3.2/qobject#event | event]]() and [[Qt:Документация 4.3.2/qevent | QEvent]].

===<div id="deleteLater"></div>void QObject::deleteLater ()  <tt> [slot]</tt>===

Schedules this object for deletion.

The object will be deleted when control returns to the event loop.

Note that entering and leaving a new event loop (e.g&#x2e;, by opening a modal dialog) will ''not'' perform the deferred deletion; for the object to be deleted, the control must return to the event loop from which deleteLater() was called.

'''Note:''' It is safe to call this function more than once; when the first deferred deletion event is delivered, any pending events for the object are removed from the event queue.

See also [[Qt:Документация 4.3.2/qobject#destroyed | destroyed]]() and [[Qt:Документация 4.3.2/qpointer | QPointer]].

===<div id="destroyed"></div>void QObject::destroyed ( QObject * ''obj'' = 0 )  <tt> [signal]</tt>===

This signal is emitted immediately before the object ''obj'' is destroyed, and can not be blocked.

All the objects's children are destroyed immediately after this signal is emitted.

See also [[Qt:Документация 4.3.2/qobject#deleteLater | deleteLater]]() and [[Qt:Документация 4.3.2/qpointer | QPointer]].

===<div id="disconnect"></div>bool QObject::disconnect ( const QObject * ''sender'', const char * ''signal'', const QObject * ''receiver'', const char * ''method'' )  <tt> [static]</tt>===

Disconnects ''signal'' in object ''sender'' from ''method'' in object ''receiver''. Returns true if the connection is successfully broken; otherwise returns false.

A signal-slot connection is removed when either of the objects involved are destroyed.

disconnect() is typically used in three ways, as the following examples demonstrate.

#Disconnect everything connected to an object's signals:<source lang="cpp-qt"> disconnect(myObject, 0, 0, 0);</source> <br />equivalent to the non-static overloaded function<br /><source lang="cpp-qt"> myObject->disconnect();</source> 
#Disconnect everything connected to a specific signal:<source lang="cpp-qt"> disconnect(myObject, SIGNAL(mySignal()), 0, 0);</source> <br />equivalent to the non-static overloaded function<br /><source lang="cpp-qt"> myObject->disconnect(SIGNAL(mySignal()));</source> 
#Disconnect a specific receiver:<source lang="cpp-qt"> disconnect(myObject, 0, myReceiver, 0);</source> <br />equivalent to the non-static overloaded function<br /><source lang="cpp-qt"> myObject->disconnect(myReceiver);</source> 

0 may be used as a wildcard, meaning "any signal", "any receiving object", or "any slot in the receiving object", respectively.

The ''sender'' may never be 0. (You cannot disconnect signals from more than one object in a single call.)

If ''signal'' is 0, it disconnects ''receiver'' and ''method'' from any signal. If not, only the specified signal is disconnected.

If ''receiver'' is 0, it disconnects anything connected to ''signal''. If not, slots in objects other than ''receiver'' are not disconnected.

If ''method'' is 0, it disconnects anything that is connected to ''receiver''. If not, only slots named ''method'' will be disconnected, and all other slots are left alone. The ''method'' must be 0 if ''receiver'' is left out, so you cannot disconnect a specifically-named slot on all objects.

'''Note:''' This function is [[Qt:Документация 4.3.2/threads#thread-safe | thread-safe]].

See also [[Qt:Документация 4.3.2/qobject#connect | connect]]().

===<div id="disconnect-2"></div>bool QObject::disconnect ( const char * ''signal'' = 0, const QObject * ''receiver'' = 0, const char * ''method'' = 0 )===

This is an overloaded member function, provided for convenience.

Disconnects ''signal'' from ''method'' of ''receiver''.

A signal-slot connection is removed when either of the objects involved are destroyed.

'''Note:''' This function is [[Qt:Документация 4.3.2/threads#thread-safe | thread-safe]].

===<div id="disconnect-3"></div>bool QObject::disconnect ( const QObject * ''receiver'', const char * ''method'' = 0 )===

This is an overloaded member function, provided for convenience.

Disconnects all signals in this object from ''receiver'''s ''method''.

A signal-slot connection is removed when either of the objects involved are destroyed.

===<div id="disconnectNotify"></div>void QObject::disconnectNotify ( const char * ''signal'' )  <tt> [virtual protected]</tt>===

This virtual function is called when something has been disconnected from ''signal'' in this object.

See [[Qt:Документация 4.3.2/qobject#connectNotify | connectNotify]]() for an example of how to compare ''signal'' with a specific signal.

'''Warning:''' This function violates the object-oriented principle of modularity. However, it might be useful for optimizing access to expensive resources.

See also [[Qt:Документация 4.3.2/qobject#disconnect | disconnect]]() and [[Qt:Документация 4.3.2/qobject#connectNotify | connectNotify]]().

===<div id="dumpObjectInfo"></div>void QObject::dumpObjectInfo ()===

Dumps information about signal connections, etc. for this object to the debug output.

This function is useful for debugging, but does nothing if the library has been compiled in release mode (i.e&#x2e; without debugging information).

See also [[Qt:Документация 4.3.2/qobject#dumpObjectTree | dumpObjectTree]]().

===<div id="dumpObjectTree"></div>void QObject::dumpObjectTree ()===

Dumps a tree of children to the debug output.

This function is useful for debugging, but does nothing if the library has been compiled in release mode (i.e&#x2e; without debugging information).

See also [[Qt:Документация 4.3.2/qobject#dumpObjectInfo | dumpObjectInfo]]().

===<div id="dynamicPropertyNames"></div>[[Qt:Документация 4.3.2/qlist | QList]]<[[Qt:Документация 4.3.2/qbytearray | QByteArray]]> QObject::dynamicPropertyNames () const===

Returns the names of all properties that were dynamically added to the object using [[Qt:Документация 4.3.2/qobject#setProperty | setProperty]]().

This function was introduced in Qt 4.2.

===<div id="event"></div>bool QObject::event ( [[Qt:Документация 4.3.2/qevent | QEvent]] * ''e'' )  <tt> [virtual]</tt>===

This virtual function receives events to an object and should return true if the event ''e'' was recognized and processed.

The event() function can be reimplemented to customize the behavior of an object.

See also [[Qt:Документация 4.3.2/qobject#installEventFilter | installEventFilter]](), [[Qt:Документация 4.3.2/qobject#timerEvent | timerEvent]](), [[Qt:Документация 4.3.2/qcoreapplication#sendEvent | QApplication::sendEvent]](), [[Qt:Документация 4.3.2/qcoreapplication#postEvent | QApplication::postEvent]](), and [[Qt:Документация 4.3.2/qwidget#event | QWidget::event]]().

===<div id="eventFilter"></div>bool QObject::eventFilter ( QObject * ''watched'', [[Qt:Документация 4.3.2/qevent | QEvent]] * ''event'' )  <tt> [virtual]</tt>===

Filters events if this object has been installed as an event filter for the ''watched'' object.

In your reimplementation of this function, if you want to filter the ''event'' out, i.e&#x2e; stop it being handled further, return true; otherwise return false.

Example:
<source lang="cpp-qt"> class MainWindow : public QMainWindow
 {
 public:
     MainWindow();

 protected:
     bool eventFilter(QObject *obj, QEvent *ev);

 private:
     QTextEdit *textEdit;
 };

 MainWindow::MainWindow()
 {
     textEdit = new QTextEdit;
     setCentralWidget(textEdit);

     textEdit->installEventFilter(this);
 }

 bool MainWindow::eventFilter(QObject *obj, QEvent *event)
 {
     if (obj == textEdit) {
         if (event->type() == QEvent::KeyPress) {
             QKeyEvent *keyEvent = static_cast<QKeyEvent*>(event);
             qDebug() << "Ate key press" << keyEvent->key();
             return true;
         } else {
             return false;
         }
     } else {
         // pass the event on to the parent class
         return QMainWindow::eventFilter(obj, event);
     }
 }</source> 
Notice in the example above that unhandled events are passed to the base class's eventFilter() function, since the base class might have reimplemented eventFilter() for its own internal purposes.

'''Warning:''' If you delete the receiver object in this function, be sure to return true. Otherwise, Qt will forward the event to the deleted object and the program might crash.

See also [[Qt:Документация 4.3.2/qobject#installEventFilter | installEventFilter]]().

===<div id="findChild"></div>T QObject::findChild ( const [[Qt:Документация 4.3.2/qstring | QString]] &amp; ''name'' = QString() ) const===

Returns the child of this object that can be cast into type T and that is called ''name'', or 0 if there is no such object. Omitting the ''name'' argument causes all object names to be matched. The search is performed recursively.

If there is more than one child matching the search, the most direct ancestor is returned. If there are several direct ancestors, it is undefined which one will be returned. In that case, [[Qt:Документация 4.3.2/qobject#findChildren | findChildren]]() should be used.

This example returns a child [[Qt:Документация 4.3.2/qpushbutton | QPushButton]] of <tt>parentWidget</tt> named <tt>"button1"</tt>:
<source lang="cpp-qt"> QPushButton *button = parentWidget->findChild<QPushButton *>("button1");</source> 
This example returns a [[Qt:Документация 4.3.2/qlistwidget | QListWidget]] child of <tt>parentWidget</tt>:
<source lang="cpp-qt"> QListWidget *list = parentWidget->findChild<QListWidget *>();</source> 
'''Warning:''' This function is not available with MSVC 6. Use [[Qt:Документация 4.3.2/qobject#qFindChild | qFindChild]]() instead if you need to support that version of the compiler.

See also [[Qt:Документация 4.3.2/qobject#findChildren | findChildren]]() and [[Qt:Документация 4.3.2/qobject#qFindChild | qFindChild]]().

===<div id="findChildren"></div>[[Qt:Документация 4.3.2/qlist | QList]]<T> QObject::findChildren ( const [[Qt:Документация 4.3.2/qstring | QString]] &amp; ''name'' = QString() ) const===

Returns all children of this object with the given ''name'' that can be cast to type T, or an empty list if there are no such objects. Omitting the ''name'' argument causes all object names to be matched. The search is performed recursively.

The following example shows how to find a list of child [[Qt:Документация 4.3.2/qwidget | QWidget]]s of the specified <tt>parentWidget</tt> named <tt>widgetname</tt>:
<source lang="cpp-qt"> QList<QWidget *> widgets = parentWidget.findChildren<QWidget *>("widgetname");</source> 
This example returns all <tt>QPushButton</tt>s that are children of <tt>parentWidget</tt>:
<source lang="cpp-qt"> QList<QPushButton *> allPButtons = parentWidget.findChildren<QPushButton *>();</source> 
'''Warning:''' This function is not available with MSVC 6. Use [[Qt:Документация 4.3.2/qobject#qFindChildren | qFindChildren]]() instead if you need to support that version of the compiler.

See also [[Qt:Документация 4.3.2/qobject#findChild | findChild]]() and [[Qt:Документация 4.3.2/qobject#qFindChildren | qFindChildren]]().

===<div id="findChildren-2"></div>[[Qt:Документация 4.3.2/qlist | QList]]<T> QObject::findChildren ( const [[Qt:Документация 4.3.2/qregexp | QRegExp]] &amp; ''regExp'' ) const===

This is an overloaded member function, provided for convenience.

Returns the children of this object that can be cast to type T and that have names matching the regular expression ''regExp'', or an empty list if there are no such objects. The search is performed recursively.

'''Warning:''' This function is not available with MSVC 6. Use [[Qt:Документация 4.3.2/qobject#qFindChildren | qFindChildren]]() instead if you need to support that version of the compiler.

===<div id="inherits"></div>bool QObject::inherits ( const char * ''className'' ) const===

Returns true if this object is an instance of a class that inherits ''className'' or a [[Qt:Документация 4.3.2/qobject | QObject]] subclass that inherits ''className''; otherwise returns false.

A class is considered to inherit itself.

Example:
<source lang="cpp-qt"> QTimer *timer = new QTimer;         // QTimer inherits QObject
 timer->inherits("QTimer");          // returns true
 timer->inherits("QObject");         // returns true
 timer->inherits("QAbstractButton"); // returns false

 // QLayout inherits QObject and QLayoutItem
 QLayout *layout = new QLayout;
 layout->inherits("QObject");        // returns true
 layout->inherits("QLayoutItem");    // returns false</source> 
([[Qt:Документация 4.3.2/qlayoutitem | QLayoutItem]] is not a [[Qt:Документация 4.3.2/qobject | QObject]].)

Consider using qobject_cast<Type *>(object) instead. The method is both faster and safer.

See also [[Qt:Документация 4.3.2/qobject#metaObject | metaObject]]() and [[Qt:Документация 4.3.2/qobject#qobject_cast | qobject_cast]]().

===<div id="installEventFilter"></div>void QObject::installEventFilter ( QObject * ''filterObj'' )===

Installs an event filter ''filterObj'' on this object. For example:
<source lang="cpp-qt"> monitoredObj->installEventFilter(filterObj);</source> 
An event filter is an object that receives all events that are sent to this object. The filter can either stop the event or forward it to this object. The event filter ''filterObj'' receives events via its [[Qt:Документация 4.3.2/qobject#eventFilter | eventFilter]]() function. The [[Qt:Документация 4.3.2/qobject#eventFilter | eventFilter]]() function must return true if the event should be filtered, (i.e&#x2e; stopped); otherwise it must return false.

If multiple event filters are installed on a single object, the filter that was installed last is activated first.

Here's a <tt>KeyPressEater</tt> class that eats the key presses of its monitored objects:
<source lang="cpp-qt">     class KeyPressEater : public QObject
     {
         Q_OBJECT
         ...

     protected:
         bool eventFilter(QObject *obj, QEvent *event);
     };

     bool KeyPressEater::eventFilter(QObject *obj, QEvent *event)
     {
         if (event->type() == QEvent::KeyPress) {
             QKeyEvent *keyEvent = static_cast<QKeyEvent *>(event);
             qDebug("Ate key press %d", keyEvent->key());
             return true;
         } else {
             // standard event processing
             return QObject::eventFilter(obj, event);
         }
     }</source> 
And here's how to install it on two widgets:
<source lang="cpp-qt">     KeyPressEater *keyPressEater = new KeyPressEater(this);
     QPushButton *pushButton = new QPushButton(this);
     QListView *listView = new QListView(this);

     pushButton->installEventFilter(keyPressEater);
     listView->installEventFilter(keyPressEater);</source> 
The [[Qt:Документация 4.3.2/qshortcut | QShortcut]] class, for example, uses this technique to intercept shortcut key presses.

'''Warning:''' If you delete the receiver object in your [[Qt:Документация 4.3.2/qobject#eventFilter | eventFilter]]() function, be sure to return true. If you return false, Qt sends the event to the deleted object and the program will crash.

'''Note:''' This function is [[Qt:Документация 4.3.2/threads#thread-safe | thread-safe]].

See also [[Qt:Документация 4.3.2/qobject#removeEventFilter | removeEventFilter]](), [[Qt:Документация 4.3.2/qobject#eventFilter | eventFilter]](), and [[Qt:Документация 4.3.2/qobject#event | event]]().

===<div id="isWidgetType"></div>bool QObject::isWidgetType () const===

Returns true if the object is a widget; otherwise returns false.

Calling this function is equivalent to calling inherits("[[Qt:Документация 4.3.2/qwidget | QWidget]]"), except that it is much faster.

===<div id="killTimer"></div>void QObject::killTimer ( int ''id'' )===

Kills the timer with timer identifier, ''id''.

The timer identifier is returned by [[Qt:Документация 4.3.2/qobject#startTimer | startTimer]]() when a timer event is started.

See also [[Qt:Документация 4.3.2/qobject#timerEvent | timerEvent]]() and [[Qt:Документация 4.3.2/qobject#startTimer | startTimer]]().

===<div id="metaObject"></div>const [[Qt:Документация 4.3.2/qmetaobject | QMetaObject]] * QObject::metaObject () const  <tt> [virtual]</tt>===

Returns a pointer to the meta-object of this object.

A meta-object contains information about a class that inherits [[Qt:Документация 4.3.2/qobject | QObject]], e.g&#x2e; class name, superclass name, properties, signals and slots. Every class that contains the [[Qt:Документация 4.3.2/qobject#Q_OBJECT | Q_OBJECT]] macro will also have a meta-object.

The meta-object information is required by the signal/slot connection mechanism and the property system. The [[Qt:Документация 4.3.2/qobject#inherits | inherits]]() function also makes use of the meta-object.

If you have no pointer to an actual object instance but still want to access the meta-object of a class, you can use [[Qt:Документация 4.3.2/qobject#staticMetaObject-var | staticMetaObject]].

Example:
<source lang="cpp-qt"> QObject *obj = new QPushButton;
 obj->metaObject()->className();             // returns "QPushButton"

 QPushButton::staticMetaObject.className();  // returns "QPushButton"</source> 
See also [[Qt:Документация 4.3.2/qobject#staticMetaObject-var | staticMetaObject]].

===<div id="moveToThread"></div>void QObject::moveToThread ( [[Qt:Документация 4.3.2/qthread | QThread]] * ''targetThread'' )===

Changes the thread affinity for this object and its children. The object cannot be moved if it has a parent. Event processing will continue in the ''targetThread''.

To move an object to the main thread, use [[Qt:Документация 4.3.2/qcoreapplication#instance | QApplication::instance]]() to retrieve a pointer to the current application, and then use [[Qt:Документация 4.3.2/qobject#thread | QApplication::thread]]() to retrieve the thread in which the application lives. For example:
<source lang="cpp-qt"> myObject->moveToThread(QApplication::instance()->thread());</source> 
If ''targetThread'' is zero, all event processing for this object and its children stops.

Note that all active timers for the object will be reset. The timers are first stopped in the current thread and restarted (with the same interval) in the ''targetThread''. As a result, constantly moving an object between threads can postpone timer events indefinitely.

A [[Qt:Документация 4.3.2/qevent#Type-enum | QEvent::ThreadChange]] event is sent to this object just before the thread affinity is changed. You can handle this event to perform any special processing. Note that any new events that are posted to this object will be handled in the ''targetThread''.

'''Warning:''' This function is ''not'' thread-safe; the current thread must be same as the current thread affinity. In other words, this function can only "push" an object from the current thread to another thread, it cannot "pull" an object from any arbitrary thread to the current thread.

See also [[Qt:Документация 4.3.2/qobject#thread | thread]]().

===<div id="parent"></div>QObject * QObject::parent () const===

Returns a pointer to the parent object.

See also [[Qt:Документация 4.3.2/qobject#setParent | setParent]]() and [[Qt:Документация 4.3.2/qobject#children | children]]().

===<div id="property"></div>[[Qt:Документация 4.3.2/qvariant | QVariant]] QObject::property ( const char * ''name'' ) const===

Returns the value of the object's ''name'' property.

If no such property exists, the returned variant is invalid.

Information about all available properties is provided through the [[Qt:Документация 4.3.2/qobject#metaObject | metaObject]]() and [[Qt:Документация 4.3.2/qobject#dynamicPropertyNames | dynamicPropertyNames]]().

See also [[Qt:Документация 4.3.2/qobject#setProperty | setProperty]](), [[Qt:Документация 4.3.2/qvariant#isValid | QVariant::isValid]](), [[Qt:Документация 4.3.2/qobject#metaObject | metaObject]](), and [[Qt:Документация 4.3.2/qobject#dynamicPropertyNames | dynamicPropertyNames]]().

===<div id="receivers"></div>int QObject::receivers ( const char * ''signal'' ) const  <tt> [protected]</tt>===

Returns the number of receivers connected to the ''signal''.

Since both slots and signals can be used as receivers for signals, and the same connections can be made many times, the number of receivers is the same as the number of connections made from this signal.

When calling this function, you can use the <tt>SIGNAL()</tt> macro to pass a specific signal:
<source lang="cpp-qt"> if (receivers(SIGNAL(valueChanged(QByteArray))) > 0) {
     QByteArray data;
     get_the_value(&amp;data);       // expensive operation
     emit valueChanged(data);
 }</source> 
As the code snippet above illustrates, you can use this function to avoid emitting a signal that nobody listens to.

'''Warning:''' This function violates the object-oriented principle of modularity. However, it might be useful when you need to perform expensive initialization only if something is connected to a signal.

===<div id="removeEventFilter"></div>void QObject::removeEventFilter ( QObject * ''obj'' )===

Removes an event filter object ''obj'' from this object. The request is ignored if such an event filter has not been installed.

All event filters for this object are automatically removed when this object is destroyed.

It is always safe to remove an event filter, even during event filter activation (i.e&#x2e; from the [[Qt:Документация 4.3.2/qobject#eventFilter | eventFilter]]() function).

'''Note:''' This function is [[Qt:Документация 4.3.2/threads#thread-safe | thread-safe]].

See also [[Qt:Документация 4.3.2/qobject#installEventFilter | installEventFilter]](), [[Qt:Документация 4.3.2/qobject#eventFilter | eventFilter]](), and [[Qt:Документация 4.3.2/qobject#event | event]]().

===<div id="sender"></div>QObject * QObject::sender () const  <tt> [protected]</tt>===

Returns a pointer to the object that sent the signal, if called in a slot activated by a signal; otherwise it returns 0. The pointer is valid only during the execution of the slot that calls this function.

The pointer returned by this function becomes invalid if the sender is destroyed, or if the slot is disconnected from the sender's signal.

'''Warning:''' This function violates the object-oriented principle of modularity. However, getting access to the sender might be useful when many signals are connected to a single slot.

See also [[Qt:Документация 4.3.2/qsignalmapper | QSignalMapper]].

===<div id="setParent"></div>void QObject::setParent ( QObject * ''parent'' )===

Makes the object a child of ''parent''.

See also [[Qt:Документация 4.3.2/qobject#parent | parent]]() and [[Qt:Документация 4.3.2/qwidget#setParent | QWidget::setParent]]().

===<div id="setProperty"></div>bool QObject::setProperty ( const char * ''name'', const [[Qt:Документация 4.3.2/qvariant | QVariant]] &amp; ''value'' )===

Sets the value of the object's ''name'' property to ''value''.

If the property is defined in the class using Q_PROPERTY then true is returned on success and false otherwise. If the property is not defined using Q_PROPERTY, and therefore not listed in the meta-object, it is added as a dynamic property and false is returned.

Information about all available properties is provided through the [[Qt:Документация 4.3.2/qobject#metaObject | metaObject]]() and [[Qt:Документация 4.3.2/qobject#dynamicPropertyNames | dynamicPropertyNames]]().

Dynamic properties can be queried again using [[Qt:Документация 4.3.2/qobject#property | property]]() and can be removed by setting the property value to an invalid [[Qt:Документация 4.3.2/qvariant | QVariant]]. Changing the value of a dynamic property causes a [[Qt:Документация 4.3.2/qdynamicpropertychangeevent | QDynamicPropertyChangeEvent]] to be sent to the object.

'''Note:''' Dynamic properties starting with "_q_" are reserved for internal purposes.

See also [[Qt:Документация 4.3.2/qobject#property | property]](), [[Qt:Документация 4.3.2/qobject#metaObject | metaObject]](), and [[Qt:Документация 4.3.2/qobject#dynamicPropertyNames | dynamicPropertyNames]]().

===<div id="signalsBlocked"></div>bool QObject::signalsBlocked () const===

Returns true if signals are blocked; otherwise returns false.

Сигналы are not blocked by default.

See also [[Qt:Документация 4.3.2/qobject#blockSignals | blockSignals]]().

===<div id="startTimer"></div>int QObject::startTimer ( int ''interval'' )===

Starts a timer and returns a timer identifier, or returns zero if it could not start a timer.

A timer event will occur every ''interval'' milliseconds until [[Qt:Документация 4.3.2/qobject#killTimer | killTimer]]() is called. If ''interval'' is 0, then the timer event occurs once every time there are no more window system events to process.

The virtual [[Qt:Документация 4.3.2/qobject#timerEvent | timerEvent]]() function is called with the [[Qt:Документация 4.3.2/qtimerevent | QTimerEvent]] event parameter class when a timer event occurs. Reimplement this function to get timer events.

If multiple timers are running, the [[Qt:Документация 4.3.2/qtimerevent#timerId | QTimerEvent::timerId]]() can be used to find out which timer was activated.

Example:
<source lang="cpp-qt"> class MyObject : public QObject
 {
     Q_OBJECT

 public:
     MyObject(QObject *parent = 0);

 protected:
     void timerEvent(QTimerEvent *event);
 };

 MyObject::MyObject(QObject *parent)
     : QObject(parent)
 {
     startTimer(50);     // 50-millisecond timer
     startTimer(1000);   // 1-second timer
     startTimer(60000);  // 1-minute timer
 }

 void MyObject::timerEvent(QTimerEvent *event)
 {
     qDebug() << "Timer ID:" << event->timerId();
 }</source> 
Note that [[Qt:Документация 4.3.2/qtimer | QTimer]]'s accuracy depends on the underlying operating system and hardware. Most platforms support an accuracy of 20 milliseconds; some provide more. If Qt is unable to deliver the requested number of timer events, it will silently discard some.

The [[Qt:Документация 4.3.2/qtimer | QTimer]] class provides a high-level programming interface with single-shot timers and timer signals instead of events. There is also a [[Qt:Документация 4.3.2/qbasictimer | QBasicTimer]] class that is more lightweight than [[Qt:Документация 4.3.2/qtimer | QTimer]] and less clumsy than using timer IDs directly.

See also [[Qt:Документация 4.3.2/qobject#timerEvent | timerEvent]](), [[Qt:Документация 4.3.2/qobject#killTimer | killTimer]](), and [[Qt:Документация 4.3.2/qtimer#singleShot | QTimer::singleShot]]().

===<div id="thread"></div>[[Qt:Документация 4.3.2/qthread | QThread]] * QObject::thread () const===

Returns the thread in which the object lives.

See also [[Qt:Документация 4.3.2/qobject#moveToThread | moveToThread]]().

===<div id="timerEvent"></div>void QObject::timerEvent ( [[Qt:Документация 4.3.2/qtimerevent | QTimerEvent]] * ''event'' )  <tt> [virtual protected]</tt>===

This event handler can be reimplemented in a subclass to receive timer events for the object.

[[Qt:Документация 4.3.2/qtimer | QTimer]] provides a higher-level interface to the timer functionality, and also more general information about timers. The timer event is passed in the ''event'' parameter.

See also [[Qt:Документация 4.3.2/qobject#startTimer | startTimer]](), [[Qt:Документация 4.3.2/qobject#killTimer | killTimer]](), and [[Qt:Документация 4.3.2/qobject#event | event]]().

===<div id="tr"></div>[[Qt:Документация 4.3.2/qstring | QString]] QObject::tr ( const char * ''sourceText'', const char * ''comment'' = 0, int ''n'' = -1 )  <tt> [static]</tt>===

Returns a translated version of ''sourceText'', or ''sourceText'' itself if there is no appropriate translated version. The translation context is Object with ''comment'' (0 by default). All [[Qt:Документация 4.3.2/qobject | QObject]] subclasses using the [[Qt:Документация 4.3.2/qobject#Q_OBJECT | Q_OBJECT]] macro automatically have a reimplementation of this function with the subclass name as context.

You can set the encoding for ''sourceText'' by calling [[Qt:Документация 4.3.2/qtextcodec#setCodecForTr | QTextCodec::setCodecForTr]](). By default ''sourceText'' is assumed to be in Latin-1 encoding.

Example:
<source lang="cpp-qt"> MyWindow::MyWindow()
 {
     QLabel *nameLabel = new QLabel(tr("Name:"));
     QLabel *addressLabel = new QLabel(tr("Address:", "i.e. a postal address"));
     ...
 }</source> 
If ''n'' >= 0, all occurrences of <tt>%n</tt> in the resulting string are replaced with a decimal representation of ''n''. In addition, depending on ''n'''s value, the translation text may vary.

Example:
<source lang="cpp-qt"> int n = messages.count();
 showMessage(tr("%n message(s) saved", "", n));</source> 
The table below shows what string is returned depending on the active translation:


{| align="center" cellpadding="2" cellspacing="1" border="0"

|- valign="top" class="qt-style" | 
!
! colspan="3" | Active Translation
|- valign="top" class="qt-style" | 
!''n''
!No Translation
!French
!English
|- valign="top" class="odd" | 
|0
|"0 message(s) saved"
|"0 message sauvegardй"
|"0 message'''s''' saved"
|- valign="top" class="even" | 
|1
|"1 message(s) saved"
|"1 message sauvegardй"
|"1 message saved"
|- valign="top" class="odd" | 
|2
|"2 message(s) saved"
|"2 message'''s''' sauvegardй'''s'''"
|"2 message'''s''' saved"
|- valign="top" class="even" | 
|37
|"37 message(s) saved"
|"37 message'''s''' sauvegardй'''s'''"
|"37 message'''s''' saved"
|}

This idiom is more flexible than the traditional approach, i.e&#x2e;,
<source lang="cpp-qt"> n == 1 ? tr("%n message saved") : tr("%n messages saved")</source> 
because it also works with target languages that have several plural forms (e.g&#x2e;, Irish has a special "dual" form that should be used when <tt>n</tt> is 2), and it handles the ''n'' == 0 case correctly for languages such as French that require the singular. See the [[Qt:Документация 4.3.2/linguist-manual | Qt Linguist Manual]] for details.

Instead of <tt>%n</tt>, you can use <tt>%Ln</tt> to produce a localized representation of ''n''. The conversion uses the default local, set using QLocal::setDefault(). (If no default locale was specified, the "C" locale is used.)

'''Warning:''' This method is reentrant only if all translators are installed ''before'' calling this method. Installing or removing translators while performing translations is not supported. Doing so will probably result in crashes or other undesirable behavior.

See also [[Qt:Документация 4.3.2/qobject#trUtf8 | trUtf8]](), [[Qt:Документация 4.3.2/qcoreapplication#translate | QApplication::translate]](), [[Qt:Документация 4.3.2/qtextcodec#setCodecForTr | QTextCodec::setCodecForTr]](), and [[Qt:Документация 4.3.2/i18n | Internationalization with Qt]].

===<div id="trUtf8"></div>[[Qt:Документация 4.3.2/qstring | QString]] QObject::trUtf8 ( const char * ''sourceText'', const char * ''comment'' = 0, int ''n'' = -1 )  <tt> [static]</tt>===

Returns a translated version of ''sourceText'', or QString::fromUtf8(''sourceText'') if there is no appropriate version. It is otherwise identical to tr(''sourceText'', ''comment'', ''n'').

'''Warning:''' This method is reentrant only if all translators are installed ''before'' calling this method. Installing or removing translators while performing translations is not supported. Doing so will probably result in crashes or other undesirable behavior.

'''Warning:''' For portability reasons, we recommend that you use escape sequences for specifying non-ASCII characters in string literals to trUtf8(). For example:
<source lang="cpp-qt"> label->setText(tr("F\374r \310lise"));</source> 
See also [[Qt:Документация 4.3.2/qobject#tr | tr]](), [[Qt:Документация 4.3.2/qcoreapplication#translate | QApplication::translate]](), and [[Qt:Документация 4.3.2/i18n | Internationalization with Qt]].
<hr />
==Member Variable Documentation==

===<div id="staticMetaObject-var"></div>const [[Qt:Документация 4.3.2/qmetaobject | QMetaObject]] QObject::staticMetaObject===

This variable stores the meta-object for the class.

A meta-object contains information about a class that inherits [[Qt:Документация 4.3.2/qobject | QObject]], e.g&#x2e; class name, superclass name, properties, signals and slots. Every class that contains the [[Qt:Документация 4.3.2/qobject#Q_OBJECT | Q_OBJECT]] macro will also have a meta-object.

The meta-object information is required by the signal/slot connection mechanism and the property system. The [[Qt:Документация 4.3.2/qobject#inherits | inherits]]() function also makes use of the meta-object.

If you have a pointer to an object, you can use [[Qt:Документация 4.3.2/qobject#metaObject | metaObject]]() to retrieve the meta-object associated with that object.

Example:
<source lang="cpp-qt"> QPushButton::staticMetaObject.className();  // returns "QPushButton"

 QObject *obj = new QPushButton;
 obj->metaObject()->className();             // returns "QPushButton"</source> 
See also [[Qt:Документация 4.3.2/qobject#metaObject | metaObject]]().
<hr />
==Связанные не-члены==

===<div id="QObjectList-typedef"></div>typedef QObjectList===

Synonym for [[Qt:Документация 4.3.2/qlist | QList]]<[[Qt:Документация 4.3.2/qobject | QObject]] *>.

===<div id="qFindChild"></div>T qFindChild ( const QObject * ''obj'', const [[Qt:Документация 4.3.2/qstring | QString]] &amp; ''name'' )===

This function is equivalent to ''obj''->[[Qt:Документация 4.3.2/qobject#findChild | findChild]]<T>(''name''). It is provided as a work-around for MSVC 6, which doesn't support member template functions.

See also [[Qt:Документация 4.3.2/qobject#findChild | QObject::findChild]]().

===<div id="qFindChildren"></div>[[Qt:Документация 4.3.2/qlist | QList]]<T> qFindChildren ( const QObject * ''obj'', const [[Qt:Документация 4.3.2/qstring | QString]] &amp; ''name'' )===

This function is equivalent to ''obj''->[[Qt:Документация 4.3.2/qobject#findChildren | findChildren]]<T>(''name''). It is provided as a work-around for MSVC 6, which doesn't support member template functions.

See also [[Qt:Документация 4.3.2/qobject#findChildren | QObject::findChildren]]().

===<div id="qFindChildren-6"></div>[[Qt:Документация 4.3.2/qlist | QList]]<T> qFindChildren ( const QObject * ''obj'', const [[Qt:Документация 4.3.2/qregexp | QRegExp]] &amp; ''regExp'' )===

This is an overloaded member function, provided for convenience.

This function is equivalent to ''obj''->[[Qt:Документация 4.3.2/qobject#findChildren | findChildren]]<T>(''regExp''). It is provided as a work-around for MSVC 6, which doesn't support member template functions.

===<div id="qobject_cast"></div>T qobject_cast ( QObject * ''object'' )===

Returns the given ''object'' cast to type T if the object is of type T (or of a subclass); otherwise returns 0.

The class T must inherit (directly or indirectly) [[Qt:Документация 4.3.2/qobject | QObject]] and be declared with the [[Qt:Документация 4.3.2/qobject#Q_OBJECT | Q_OBJECT]] macro.

A class is considered to inherit itself.

Example:
<source lang="cpp-qt"> QObject *obj = new QTimer;          // QTimer inherits QObject

 QTimer *timer = qobject_cast<QTimer *>(obj);
 // timer == (QObject *)obj

 QAbstractButton *button = qobject_cast<QAbstractButton *>(obj);
 // button == 0</source> 
The qobject_cast() function behaves similarly to the standard C++ <tt>dynamic_cast()</tt>, with the advantages that it doesn't require RTTI support and it works across dynamic library boundaries.

qobject_cast() can also be used in conjunction with interfaces; see the [[Qt:Документация 4.3.2/tools-plugandpaint | Plug &amp; Paint]] example for details.

'''Warning:''' If T isn't declared with the [[Qt:Документация 4.3.2/qobject#Q_OBJECT | Q_OBJECT]] macro, this function's return value is undefined.

See also [[Qt:Документация 4.3.2/qobject#inherits | QObject::inherits]]().
<hr />
==Macro Documentation==

===<div id="Q_CLASSINFO"></div>Q_CLASSINFO (  ''Name'',  ''Value'' )===

This macro associates extra information to the class, which is available using [[Qt:Документация 4.3.2/qobject#metaObject | QObject::metaObject]](). Except for the [[Qt:Документация 4.3.2/activeqt#activeqt | ActiveQt]] extension, Qt doesn't use this information.

The extra information takes the form of a ''Name'' string and a ''Value'' literal string.

Example:
<source lang="cpp-qt"> class MyClass : public QObject
 {
     Q_OBJECT
     Q_CLASSINFO("Author", "Pierre Gendron")
     Q_CLASSINFO("URL", "http://www.my-organization.qc.ca")

 public:
     ...
 };</source> 
See also [[Qt:Документация 4.3.2/qmetaobject#classInfo | QMetaObject::classInfo]]().

===<div id="Q_ENUMS"></div>Q_ENUMS ( ... )===

This macro registers one or several enum types to the meta-object system.

For example:
<source lang="cpp-qt"> class MyClass : public QObject
 {
     Q_OBJECT
     Q_ENUMS(Priority)

 public:
     MyClass(QObject *parent = 0);
     ~MyClass();

     enum Priority { High, Low, VeryHigh, VeryLow };
     void setPriority(Priority priority);
     Priority priority() const;
 };</source> 
If you want to register an enum that is declared in another class, the enum must be fully qualified with the name of the class defining it. In addition, the class ''defining'' the enum has to inherit [[Qt:Документация 4.3.2/qobject | QObject]] as well as declare the enum using Q_ENUMS().

See also [[Qt:Документация 4.3.2/properties | Qt's Property System]].

===<div id="Q_FLAGS"></div>Q_FLAGS ( ... )===

This macro registers one or several "flags" types to the meta-object system.

Example:
<source lang="cpp-qt"> Q_FLAGS(Options Alignment)</source> 
See also [[Qt:Документация 4.3.2/properties | Qt's Property System]].

===<div id="Q_INTERFACES"></div>Q_INTERFACES ( ... )===

This macro tells Qt which interfaces the class implements. This is used when implementing plugins.

Example:
<source lang="cpp-qt"> class BasicToolsPlugin : public QObject,
                          public BrushInterface,
                          public ShapeInterface,
                          public FilterInterface
 {
     Q_OBJECT
     Q_INTERFACES(BrushInterface ShapeInterface FilterInterface)

 public:
     ...
 };</source> 
See the [[Qt:Документация 4.3.2/tools-plugandpaintplugins-basictools | Plug &amp; Paint Basic Tools]] example for details.

See also [[Qt:Документация 4.3.2/qtplugin#Q_DECLARE_INTERFACE | Q_DECLARE_INTERFACE]](), [[Qt:Документация 4.3.2/qtplugin#Q_EXPORT_PLUGIN2 | Q_EXPORT_PLUGIN2]](), and [[Qt:Документация 4.3.2/plugins-howto | How to Create Qt Plugins]].

===<div id="Q_OBJECT"></div>Q_OBJECT===

The Q_OBJECT macro must appear in the private section of a class definition that declares its own signals and slots or that uses other services provided by Qt's meta-object system.

For example:
<source lang="cpp-qt"> #include <QObject>

 class Counter : public QObject
 {
     Q_OBJECT

 public:
     Counter() { m_value = 0; }

     int value() const { return m_value; }

 public slots:
     void setValue(int value);

 signals:
     void valueChanged(int newValue);

 private:
     int m_value;
 };</source> 
See also [[Qt:Документация 4.3.2/metaobjects | Meta-Object System]], [[Qt:Документация 4.3.2/signalsandslots | Сигналы and Slots]], and [[Qt:Документация 4.3.2/properties | Qt's Property System]].

===<div id="Q_PROPERTY"></div>Q_PROPERTY ( ... )===

This macro declares a [[Qt:Документация 4.3.2/qobject | QObject]] property. The syntax is:
<source lang="cpp-qt"> Q_PROPERTY(type name
            READ getFunction
            [WRITE setFunction]
            [RESET resetFunction]
            [DESIGNABLE bool]
            [SCRIPTABLE bool]
            [STORED bool])</source> 
For example:
<source lang="cpp-qt"> Q_PROPERTY(QString title READ title WRITE setTitle)</source> 
See also [[Qt:Документация 4.3.2/properties | Qt's Property System]].

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