Provides an interface for monitoring files and directories for modifications. More...

Inheritance diagram for QFileSystemWatcher:

Public Signals
void	directoryChanged (const QString &path)

void	fileChanged (const QString &path)

Public Signals inherited from QObject
void	destroyed (QObject *obj=nullptr)

void	objectNameChanged (const QString &objectName)

Public Methods
	QFileSystemWatcher (const QStringList &pathList, QObject *parent=nullptr)

	QFileSystemWatcher (QObject *parent=nullptr)

	~QFileSystemWatcher ()

void	addPath (const QString &path)

void	addPaths (const QStringList &pathList)

QStringList	directories () const

QStringList	files () const

void	removePath (const QString &path)

void	removePaths (const QStringList &pathList)

Public Methods inherited from QObject
	QObject (QObject *parent=nullptr)

	~QObject ()

bool	blockSignals (bool block)

const QList< QObject * > &	children () const

bool	connect (const QObject *sender, const QString &signalMethod, const QString &location, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

bool	connect (const QObject *sender, const QString &signalMethod, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

bool	disconnect (const QObject *receiver, const QString &slotMethod=QString ()) const

bool	disconnect (const QString &signalMethod, const QString &location, const QObject *receiver=nullptr, const QString &slotMethod=QString ()) const

bool	disconnect (const QString &signalMethod=QString (), const QObject *receiver=nullptr, const QString &slotMethod=QString ()) const

void	dumpObjectInfo ()

void	dumpObjectTree ()

QList< QString >	dynamicPropertyNames () const

virtual bool	event (QEvent *event)

virtual bool	eventFilter (QObject watched, QEvent event)

template<typename T >
T	findChild (const QString &childName=QString ()) const

template<class T >
QList< T >	findChildren (const QRegularExpression &regExp, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const

template<class T >
QList< T >	findChildren (const QString &childName=QString (), Qt::FindChildOptions options=Qt::FindChildrenRecursively) const

bool	inherits (const QString &className) const

void	installEventFilter (QObject *filterObj)

bool	isWidgetType () const

bool	isWindowType () const

void	killTimer (int id)

const QMetaObject *	metaObject () const

void	moveToThread (QThread *targetThread)

QString	objectName () const

QObject *	parent () const

template<class T = QVariant>
T	property (const QString &name) const

void	removeEventFilter (QObject *obj)

void	setObjectName (const QString &name)

void	setParent (QObject *parent)

bool	setProperty (const QString &name, const QVariant &value)

bool	signalsBlocked () const

int	startTimer (int interval, Qt::TimerType timerType=Qt::CoarseTimer)

QThread *	thread () const

Additional Inherited Members
Public Slots inherited from QObject
void	deleteLater ()

Static Public Methods inherited from QObject
static bool	connect (const QObject sender, const QMetaMethod &signalMethod, const QObject receiver, const QMetaMethod &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

static bool	connect (const QObject sender, const QString &signalMethod, const QObject receiver, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection, const QString &location=QString ())

static bool	connect (const QObject sender, const QString &signalMethod, const QString &location, const QObject receiver, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class SlotClass , class... SlotArgs, class SlotReturn >
static bool	connect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver receiver, SlotReturn (SlotClass::slotMethod)(SlotArgs...), Qt::ConnectionType type=Qt::AutoConnection)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class T >
static bool	connect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver *receiver, T slotLambda, Qt::ConnectionType type=Qt::AutoConnection)

static bool	disconnect (const QObject sender, const QMetaMethod &signalMethod, const QObject receiver, const QMetaMethod &slotMethod)

static bool	disconnect (const QObject sender, const QString &signalMethod, const QObject receiver, const QString &slotMethod)

static bool	disconnect (const QObject sender, const QString &signalMethod, const QString &location, const QObject receiver, const QString &slotMethod)

static bool	disconnect (const QObject sender, std::nullptr_t, const QObject receiver, std::nullptr_t)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class SlotClass , class... SlotArgs, class SlotReturn >
static bool	disconnect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver receiver, SlotReturn (SlotClass::slotMethod)(SlotArgs...))

template<class Sender , class SignalClass , class... SignalArgs, class Receiver >
static bool	disconnect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver *receiver, std::nullptr_t slotMethod=nullptr)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class T >
static bool	disconnect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver *receiver, T slotMethod)

static QMetaObject &	staticMetaObject ()

static QString	tr (const char text, const char comment=nullptr, std::optional< int > numArg=std::optional< int >())

Protected Methods inherited from QObject
virtual void	childEvent (QChildEvent *event)

virtual void	connectNotify (const QMetaMethod &signalMethod) const

virtual void	customEvent (QEvent *event)

virtual void	disconnectNotify (const QMetaMethod &signalMethod) const

bool	isSignalConnected (const QMetaMethod &signalMethod) const

int	receivers (const QString &signal) const

QObject *	sender () const

int	senderSignalIndex () const

virtual void	timerEvent (QTimerEvent *event)

Properties inherited from QObject
	objectName

Related Functions inherited from QObject
T	qobject_cast (QObject *object)

	QObjectList

Detailed Description

The QFileSystemWatcher class provides an interface for monitoring files and directories for modifications. QFileSystemWatcher monitors the file system for changes to files and directories by watching a list of specified path locations.

Call addPath() to watch a particular file or directory. Multiple paths can be added using the addPaths() method. Existing paths can be removed by using the removePath() and removePaths() methods. QFileSystemWatcher examines each path added to it. Files that have been added to the QFileSystemWatcher can be accessed using the files() method, and directories using the directories() method.

The fileChanged() signal is emitted when a file has been modified, renamed or removed from disk. Similarly, the directoryChanged() signal is emitted when a directory or its contents is modified or removed. QFileSystemWatcher stops monitoring files once they have been renamed or removed from disk, and directories once they have been removed from disk.

On systems running Linux without inotify support, file systems that contain watched paths can not be unmounted.

Monitoring files and directories for modifications consumes system resources. This implies there is a limit to the number of files and directories your process can monitor simultaneously. On some platforms an open file descriptor is required for each monitored file. Some system limits the number of open file descriptors to 256 by default. This means that addPath() and addPaths() will fail if your process tries to add more than 256 files or directories to the file system monitor. Your process may have other file descriptors open in addition to the ones for files being monitored, and these other open descriptors also count in the total.

See also: QFile, QDir

Constructor & Destructor Documentation

QFileSystemWatcher::QFileSystemWatcher ( QObject * parent = nullptr )

Constructs a new file system watcher object with the given parent.

QFileSystemWatcher::QFileSystemWatcher	(	const QStringList &	pathList,
		QObject *	parent = `nullptr`
	)

Constructs a new file system watcher object with the given parent which monitors the specified pathList.

QFileSystemWatcher::~QFileSystemWatcher ( )

Destroys the file system watcher.

Method Documentation

void QFileSystemWatcher::addPath ( const QString & path )

Adds path to the file system watcher if it exists. The path is not added if it does not exist, or if it is already being monitored by the file system watcher. If path specifies a directory, the directoryChanged() signal will be emitted when path is modified or removed from disk, otherwise the fileChanged() signal is emitted when path is modified, renamed or removed.

Note: There is a system dependent limit to the number of files and directories that can be monitored simultaneously. If this limit has been reached, path will not be added to the file system watcher, and a warning message will be printed to stderr.

See also: addPaths(), removePath()

void QFileSystemWatcher::addPaths ( const QStringList & pathList )

Adds each path in pathList to the file system watcher. Paths are not added if they not exist, or if they are already being monitored by the file system watcher. If a path specifies a directory, the directoryChanged() signal will be emitted when the path is modified or removed from disk, otherwise the fileChanged() signal is emitted when the path is modified, renamed, or removed.

Note: There is a system dependent limit to the number of files and directories that can be monitored simultaneously. If this limit has been reached, the excess pathList will not be added to the file system watcher, and a warning message will be printed to stderr for each path that could not be added.

See also: addPath(), removePaths()

QStringList QFileSystemWatcher::directories ( ) const

Returns a list of paths to directories that are being watched.

See also: files()

void QFileSystemWatcher::directoryChanged ( const QString & path )

signal

This signal is emitted when the directory at a specified path, is modified (e.g., when a file is added, modified or deleted) or removed from disk. If there are several changes during a short period of time, some of the changes might not emit this signal. However, the last change in the sequence of changes will always generate this signal.