內容

• 公共函數
• 詳細描述

QDBusContext 類

The QDBusContext 類允許槽確定調用的 D-Bus 上下文。 更多...

頭：	#include <QDBusContext>
qmake:	QT += dbus
Since:	Qt 4.3

• 所有成員列錶，包括繼承成員

公共函數

	QDBusContext ()
	~QDBusContext ()
bool	calledFromDBus () const
QDBusConnection	connection () const
bool	isDelayedReply () const
const QDBusMessage &	message () const
void	sendErrorReply (const QString & name , const QString & msg = QString()) const
void	sendErrorReply (QDBusError::ErrorType type , const QString & msg = QString()) const
void	setDelayedReply (bool enable ) const

詳細描述

The QDBusContext 類允許槽確定調用的 D-Bus 上下文。

When a slot is called in an object due to a signal delivery or due to a remote method call, it is sometimes necessary to know the context in which that happened. In particular, if the slot determines that it wants to send the reply at a later opportunity or if it wants to reply with an error, the context is needed.

The QDBusContext class is an alternative to accessing the context that doesn't involve modifying the code generated by the Qt D-Bus XML 編譯器 (qdbusxml2cpp) .

QDBusContext is used by subclassing it from the objects being exported using QDBusConnection::registerObject ()。以下範例闡明用法：

class MyObject: public QObject,
                protected QDBusContext
{
    Q_OBJECT
    QDBusConnection conn;
    QDBusMessage msg;
...
protected slots:
    void process();
public slots:
    void methodWithError();
    QString methodWithDelayedReply();
};
void MyObject::methodWithError()
{
    sendErrorReply(QDBusError::NotSupported,
                   "The method call 'methodWithError()' is not supported");
}
QString MyObject::methodWithDelayedReply()
{
    conn = connection();
    msg = message();
    setDelayedReply(true);
    QMetaObject::invokeMethod(this, "process", Qt::QueuedConnection);
    return QString();
}
					

The example illustrates the two typical uses, that of sending error replies and that of delayed replies.

Note: do not subclass QDBusContext and QDBusAbstractAdaptor at the same time. QDBusContext should appear in the real object, not the adaptor. If it's necessary from the adaptor code to determine the context, use a public inheritance and access the functions via QObject::parent ().

成員函數文檔編製

QDBusContext:: QDBusContext ()

構造空的 QDBusContext .

QDBusContext:: ~QDBusContext ()

空的析構函數。

bool QDBusContext:: calledFromDBus () const

返迴 true if we are processing a D-Bus call. If this function returns true , the rest of the functions in this class are available.

Accessing those functions when this function returns false is undefined and may lead to crashes.

QDBusConnection QDBusContext:: connection () const

Returns the connection from which this call was received.

bool QDBusContext:: isDelayedReply () const

返迴 true 若此調用會擁有延遲迴復。

另請參閱 setDelayedReply ().

const QDBusMessage &QDBusContext:: message () const

Returns the message that generated this call.

void QDBusContext:: sendErrorReply (const QString & name , const QString & msg = QString()) const

發送錯誤 name as a reply to the caller. The optional msg parameter is a human-readable text explaining the failure.

If an error is sent, the return value and any output parameters from the called slot will be ignored by Qt D-Bus.

void QDBusContext:: sendErrorReply ( QDBusError::ErrorType type , const QString & msg = QString()) const

這是重載函數。

發送錯誤 type as a reply to the caller. The optional msg parameter is a human-readable text explaining the failure.

If an error is sent, the return value and any output parameters from the called slot will be ignored by Qt D-Bus.

void QDBusContext:: setDelayedReply ( bool enable ) const

Sets whether this call will have a delayed reply or not.

若 enable is false, Qt D-Bus will automatically generate a reply back to the caller, if needed, as soon as the called slot returns.

若 enable is true, Qt D-Bus will not generate automatic replies. It will also ignore the return value from the slot and any output parameters. Instead, the called object is responsible for storing the incoming message and send a reply or error at a later time.

Failing to send a reply will result in an automatic timeout error being generated by D-Bus.

另請參閱 isDelayedReply ().