QDBusPendingReply 类包含异步方法调用的回复。 更多...
| 头： | #include <QDBusPendingReply> |
| CMake: |
find_package(Qt6 REQUIRED COMPONENTS DBus)
target_link_libraries(mytarget PRIVATE Qt6::DBus) |
| qmake: | QT += dbus |
| 继承： | QDBusPendingReplyBase |
| enum | anonymous { Count } |
| QDBusPendingReply () | |
| QDBusPendingReply (const QDBusPendingCall & call ) | |
| QDBusPendingReply (const QDBusMessage & message ) | |
| QDBusPendingReply (const QDBusPendingReply<Types...> & other ) | |
| QVariant | argumentAt (int index ) const |
| int | count () const |
| QDBusError | error () const |
| bool | isError () const |
| bool | isFinished () const |
| bool | isValid () const |
| QDBusMessage | reply () const |
| typename Select<0>::Type | value () const |
| void | waitForFinished () |
| typename Select<0>::Type | operator typename Select<0>::Type () const |
| QDBusPendingReply<Types...> & | operator= (const QDBusPendingReply<Types...> & other ) |
| QDBusPendingReply<Types...> & | operator= (const QDBusPendingCall & call ) |
| QDBusPendingReply<Types...> & | operator= (const QDBusMessage & message ) |
The QDBusPendingReply is a variadic template class. The template parameters are the types that will be used to extract the contents of the reply's data.
This class is similar in functionality to QDBusReply , but with two important differences:
Where with QDBusReply you would write:
QDBusReply<QString> reply = interface->call("RemoteMethod"); if (reply.isValid()) // use the returned value useValue(reply.value()); else // call failed. Show an error condition. showError(reply.error());
with QDBusPendingReply, the equivalent code (including the blocking wait for the reply) would be:
QDBusPendingReply<QString> reply = iface->asyncCall("RemoteMethod");
reply.waitForFinished();
if (reply.isError())
// call failed. Show an error condition.
showErrorD(reply.error());
else
// use the returned value
useValue(reply.value());
For method calls that have more than one output argument, with QDBusReply , you would write:
reply = interface->call("RemoteMethod");
whereas with QDBusPendingReply, all of the output arguments should be template parameters:
QDBusPendingReply<bool, QString> reply = iface->asyncCall("RemoteMethod");
reply.waitForFinished();
if (!reply.isError()) {
if (reply.argumentAt<0>())
showSuccess(reply.argumentAt<1>());
else
showFailure(reply.argumentAt<1>());
}
QDBusPendingReply objects can be associated with QDBusPendingCallWatcher objects, which emit signals when the reply arrives.
另请参阅 QDBusPendingCallWatcher and QDBusReply .
| 常量 | 值 | 描述 |
|---|---|---|
QDBusPendingReply::Count
|
std::is_same_v<typename Select<0>::Type, void> ? 0 : sizeof...(Types)
|
The number of arguments the reply is expected to have |
Creates an empty QDBusPendingReply object. Without assigning a QDBusPendingCall object to this reply, QDBusPendingReply cannot do anything. All functions return their failure values.
Creates a QDBusPendingReply object that will take its contents from the call pending asynchronous call. This QDBusPendingReply object will share the same pending call reference as call .
Creates a QDBusPendingReply object that will take its contents from the message message . In this case, this object will be already in its finished state and the reply's contents will be accessible.
另请参阅 isFinished ().
创建副本为 other QDBusPendingReply object. Just like QDBusPendingCall and QDBusPendingCallWatcher , this QDBusPendingReply object will share the same pending call reference. All copies share the same return values.
Returns the argument at position index in the reply's contents. If the reply doesn't have that many elements, this function's return value is undefined (will probably cause an assertion failure), so it is important to verify that the processing is finished and the reply is valid.
If the reply does not contain an argument at position index or if the reply was an error, this function returns an invalid QVariant . Since D-Bus messages can never contain invalid QVariants, this return can be used to detect an error condition.
[constexpr]
int
QDBusPendingReply::
count
() const
Return the number of arguments the reply is supposed to have. This number matches the number of non-void template parameters in this class.
If the reply arrives with a different number of arguments (or with different types), it will be transformed into an error reply indicating a bad signature.
Retrieves the error content of the reply message, if it has finished processing. If the reply message has not finished processing or if it contains a normal reply message (non-error), this function returns an invalid QDBusError .
返回
true
if the reply contains an error message, false if it contains a normal method reply.
If the pending call has not finished processing, this function also returns
true
.
返回
true
if the pending call has finished processing and the reply has been received. If this function returns
true
，
isError
(),
error
() 和
reply
() methods should return valid information.
Note that this function only changes state if you call waitForFinished () or if an external D-Bus event happens, which in general only happens if you return to the event loop execution.
另请参阅 QDBusPendingCallWatcher::isFinished ().
返回
true
if the reply contains a normal reply message, false if it contains anything else.
If the pending call has not finished processing, this function return false.
Retrieves the reply message received for the asynchronous call that was sent, if it has finished processing. If the pending call is not finished, this function returns a QDBusMessage 类型 QDBusMessage::InvalidMessage .
After it has finished processing, the message type will either be an error message or a normal method reply message.
Returns the first argument in this reply, cast to type
Types[0]
(the first template parameter of this class). This is equivalent to calling
argumentAt
<0>().
This function is provided as a convenience, matching the QDBusReply::value () 函数。
Note that, if the reply hasn't arrived, this function causes the calling thread to block until the reply is processed.
If the reply is an error reply, this function returns a default-constructed
Types[0]
object, which may be indistinguishable from a valid value. To reliably determine whether the message was an error, use
isError
().
Suspends the execution of the calling thread until the reply is received and processed. After this function returns, isFinished () should return true, indicating the reply's contents are ready to be processed.
另请参阅 QDBusPendingCallWatcher::waitForFinished ().
Returns the first argument in this reply, cast to type
Types[0]
(the first template parameter of this class). This is equivalent to calling
argumentAt
<0>().
This function is provided as a convenience, matching the QDBusReply::value () 函数。
Note that, if the reply hasn't arrived, this function causes the calling thread to block until the reply is processed.
If the reply is an error reply, this function returns a default-constructed
Types[0]
object, which may be indistinguishable from a valid value. To reliably determine whether the message was an error, use
isError
().
制作副本为 other and drops the reference to the current pending call. If the current reference is to an unfinished pending call and this is the last reference, the pending call will be canceled and there will be no way of retrieving the reply's contents, when they arrive.
Makes this object take its contents from the call pending call and drops the reference to the current pending call. If the current reference is to an unfinished pending call and this is the last reference, the pending call will be canceled and there will be no way of retrieving the reply's contents, when they arrive.
Makes this object take its contents from the message message and drops the reference to the current pending call. If the current reference is to an unfinished pending call and this is the last reference, the pending call will be canceled and there will be no way of retrieving the reply's contents, when they arrive.
After this function is finished, the QDBusPendingReply object will be in its "finished" state and the message contents will be accessible.
另请参阅 isFinished ().