QMetaMethod 類

QMetaMethod 類提供有關成員函數的元數據。 更多...

頭：	#include <QMetaMethod>
CMake:	find_package(Qt6 REQUIRED COMPONENTS Core) target_link_libraries(mytarget PRIVATE Qt6::Core)
qmake:	QT += core

• 所有成員列錶，包括繼承成員
• 棄用成員

此類 相等可比較 .

公共類型

enum	Access { Private, Protected, Public }
enum	MethodType { Method, Signal, Slot, Constructor }

公共函數

QMetaMethod::Access	access () const
(從 6.5 起) bool	invoke (QObject * obj , Args &&... arguments ) const
(從 6.5 起) bool	invoke (QObject * obj , QTemplatedMetaMethodReturnArgument<ReturnArg> ret , Args &&... arguments ) const
(從 6.5 起) bool	invoke (QObject * obj , Qt::ConnectionType type , Args &&... arguments ) const
(從 6.5 起) bool	invoke (QObject * obj , Qt::ConnectionType type , QTemplatedMetaMethodReturnArgument<ReturnArg> ret , Args &&... arguments ) const
(從 6.5 起) bool	invokeOnGadget (void * gadget , Args &&... arguments ) const
(從 6.5 起) bool	invokeOnGadget (void * gadget , QTemplatedMetaMethodReturnArgument<ReturnArg> ret , Args &&... arguments ) const
(從 6.2 起) bool	isConst () const
bool	isValid () const
int	methodIndex () const
QByteArray	methodSignature () const
QMetaMethod::MethodType	methodType () const
QByteArray	name () const
int	parameterCount () const
(從 6.0 起) QMetaType	parameterMetaType (int index ) const
QList<QByteArray>	parameterNames () const
int	parameterType (int index ) const
(從 6.0 起) QByteArray	parameterTypeName (int index ) const
QList<QByteArray>	parameterTypes () const
(從 6.0 起) int	relativeMethodIndex () const
(從 6.0 起) QMetaType	returnMetaType () const
int	returnType () const
int	revision () const
const char *	tag () const
const char *	typeName () const

靜態公共成員

QMetaMethod

fromSignal (PointerToMemberFunction signal )

相關非成員

bool	operator!= (const QMetaMethod & lhs , const QMetaMethod & rhs )
bool	operator== (const QMetaMethod & lhs , const QMetaMethod & rhs )

宏

Q_METAMETHOD_INVOKE_MAX_ARGS

詳細描述

QMetaMethod 擁有 methodType ()， methodSignature (), 列錶化的 parameterTypes () 和 parameterNames (), a return typeName ()， tag (), and an access () specifier. You can use invoke () to invoke the method on an arbitrary QObject .

另請參閱 QMetaObject , QMetaEnum , QMetaProperty ，和 Qt 的特性係統 .

成員類型文檔編製

enum QMetaMethod:: Access

This enum describes the access level of a method, following the conventions used in C++.

常量	值
QMetaMethod::Private	0
QMetaMethod::Protected	1
QMetaMethod::Public	2

enum QMetaMethod:: MethodType

常量	值	描述
QMetaMethod::Method	0	函數是純成員函數。
QMetaMethod::Signal	1	函數是信號。
QMetaMethod::Slot	2	函數是槽。
QMetaMethod::Constructor	3	函數是構造函數。

成員函數文檔編製

[since 6.5] template <typename... Args> bool QMetaMethod:: invoke ( QObject * obj , Args &&... arguments ) const

[since 6.5] template <typename ReturnArg, typename... Args> bool QMetaMethod:: invoke ( QObject * obj , QTemplatedMetaMethodReturnArgument < ReturnArg > ret , Args &&... arguments ) const

[since 6.5] template <typename... Args> bool QMetaMethod:: invoke ( QObject * obj , Qt::ConnectionType type , Args &&... arguments ) const

[since 6.5] template <typename ReturnArg, typename... Args> bool QMetaMethod:: invoke ( QObject * obj , Qt::ConnectionType type , QTemplatedMetaMethodReturnArgument < ReturnArg > ret , Args &&... arguments ) const

Invokes this method on the object object 。返迴 true 若成員可以被援引。返迴 false 若沒有這樣的成員或參數不匹配。

對於具有 QTemplatedMetaMethodReturnArgument 參數的重載，返迴值對於 member 函數調用被放置在 ret . For the overloads without such a member, the return value of the called function (if any) will be discarded. QTemplatedMetaMethodReturnArgument is an internal type you should not use directly. Instead, use the qReturnArg() function.

重載采用 Qt::ConnectionType type 參數允許明確選擇是否將同步援引：

• 若 type is Qt::DirectConnection ， 成員將在當前綫程中被立即援引。
• 若 type is Qt::QueuedConnection ， QEvent will be sent and the member is invoked as soon as the application enters the event loop in the thread the obj 在其中被創建或被移動到。
• 若 type is Qt::BlockingQueuedConnection , the method will be invoked in the same way as for Qt::QueuedConnection , except that the current thread will block until the event is delivered. Using this connection type to communicate between objects in the same thread will lead to deadlocks.
• 若 type is Qt::AutoConnection , the member is invoked synchronously if obj lives in the same thread as the caller; otherwise it will invoke the member asynchronously. This is the behavior of the overloads that do not have the type 參數。

To asynchronously invoke the animateClick () slot on a QPushButton :

int methodIndex = pushButton->metaObject()->indexOfMethod("animateClick()");
QMetaMethod method = metaObject->method(methodIndex);
method.invoke(pushButton, Qt::QueuedConnection);
					

With asynchronous method invocations, the parameters must be copyable types, because Qt needs to copy the arguments to store them in an event behind the scenes. Since Qt 6.5, this function automatically registers the types being used; however, as a side-effect, it is not possible to make calls using types that are only forward-declared. Additionally, it is not possible to make asynchronous calls that use references to non-const-qualified types as parameters either.

要同步援引 compute(QString, int, double) 槽在某些任意對象 obj 檢索其返迴值：

QString retVal;
QByteArray normalizedSignature = QMetaObject::normalizedSignature("compute(QString, int, double)");
int methodIndex = obj->metaObject()->indexOfMethod(normalizedSignature);
QMetaMethod method = obj->metaObject()->method(methodIndex);
method.invoke(obj, Qt::DirectConnection, qReturnArg(retVal),
              QString("sqrt"), 42, 9.7);
					

若 compute 槽不接受 1 個準確 QString , one int ，和 1 個 double in the specified order, the call will fail. Note how it was necessary to be explicit about the type of the QString , as the character literal is not exactly the right type to match. If the method instead took a QByteArray ， qint64 ，和 long double , the call would need to be written as:

QString retVal;
QByteArray normalizedSignature = QMetaObject::normalizedSignature("compute(QByteArray, qint64, long double)");
int methodIndex = obj->metaObject()->indexOfMethod(normalizedSignature);
QMetaMethod method = obj->metaObject()->method(methodIndex);
method.invoke(obj, Qt::DirectConnection, qReturnArg(retVal),
              QByteArray("sqrt"), qint64(42), 9.7L);
					

The same call can be executed using the Q_ARG () 和 Q_RETURN_ARG () macros, as in:

QString retVal;
QByteArray normalizedSignature = QMetaObject::normalizedSignature("compute(QString, int, double)");
int methodIndex = obj->metaObject()->indexOfMethod(normalizedSignature);
QMetaMethod method = obj->metaObject()->method(methodIndex);
method.invoke(obj,
              Qt::DirectConnection,
              Q_RETURN_ARG(QString, retVal),
              Q_ARG(QString, "sqrt"),
              Q_ARG(int, 42),
              Q_ARG(double, 9.7));
					

警告： this method will not test the validity of the arguments: object must be an instance of the class of the QMetaObject of which this QMetaMethod has been constructed with.

該函數在 Qt 6.5 引入。

另請參閱 Q_ARG (), Q_RETURN_ARG (), qRegisterMetaType ()，和 QMetaObject::invokeMethod ().

[since 6.5] template <typename... Args> bool QMetaMethod:: invokeOnGadget ( void * gadget , Args &&... arguments ) const

[since 6.5] template <typename ReturnArg, typename... Args> bool QMetaMethod:: invokeOnGadget ( void * gadget , QTemplatedMetaMethodReturnArgument < ReturnArg > ret , Args &&... arguments ) const

Invokes this method on a Q_GADGET 。返迴 true 若成員可以被援引。返迴 false 若沒有這樣的成員或參數不匹配。

指針 gadget must point to an instance of the gadget class.

援引始終是同步的。

For the overload with a QTemplatedMetaMethodReturnArgument parameter, the return value of the member 函數調用被放置在 ret . For the overload without it, the return value of the called function (if any) will be discarded. QTemplatedMetaMethodReturnArgument is an internal type you should not use directly. Instead, use the qReturnArg() function.

警告： this method will not test the validity of the arguments: gadget must be an instance of the class of the QMetaObject of which this QMetaMethod has been constructed with.

該函數在 Qt 6.5 引入。

另請參閱 Q_ARG (), Q_RETURN_ARG (), qRegisterMetaType ()，和 QMetaObject::invokeMethod ().

QMetaMethod::Access QMetaMethod:: access () const

Returns the access specification of this method (private, protected, or public).

注意： Signals are always public, but you should regard that as an implementation detail. It is almost always a bad idea to emit a signal from outside its class.

另請參閱 methodType ().

[static] template <typename PointerToMemberFunction> QMetaMethod QMetaMethod:: fromSignal ( PointerToMemberFunction signal )

返迴的元方法相當於給定 signal ，或無效 QMetaMethod if signal is nullptr or not a signal of the class.

範例：

QMetaMethod destroyedSignal = QMetaMethod::fromSignal(&QObject::destroyed);
					

[since 6.2] bool QMetaMethod:: isConst () const

Returns whether the method is const qualified.

注意： This method might erroneously return false for a const method if it belongs to a library compiled against an older version of Qt.

該函數在 Qt 6.2 引入。

bool QMetaMethod:: isValid () const

返迴 true if this method is valid (can be introspected and invoked), otherwise returns false .

int QMetaMethod:: methodIndex () const

返迴此方法的索引。

QByteArray QMetaMethod:: methodSignature () const

返迴此方法的簽名 (如 setValue(double) ).

另請參閱 parameterTypes () 和 parameterNames ().

QMetaMethod::MethodType QMetaMethod:: methodType () const

返迴此方法 (信號、槽或方法) 的類型。

另請參閱 access ().

QByteArray QMetaMethod:: name () const

返迴此方法的名稱。

另請參閱 methodSignature () 和 parameterCount ().

int QMetaMethod:: parameterCount () const

返迴此方法的參數數。

另請參閱 parameterType () 和 parameterNames ().

[since 6.0] QMetaType QMetaMethod:: parameterMetaType ( int index ) const

Returns the metatype of the parameter at the given index .

若 index is smaller than zero or larger than parameterCount (), an invalid QMetaType 被返迴。

該函數在 Qt 6.0 引入。

另請參閱 parameterCount (), returnMetaType ()，和 QMetaType .

QList < QByteArray > QMetaMethod:: parameterNames () const

返迴參數名稱的列錶。

另請參閱 parameterTypes () 和 methodSignature ().

int QMetaMethod:: parameterType ( int index ) const

Returns the type of the parameter at the given index .

The return value is one of the types that are registered with QMetaType ，或 QMetaType::UnknownType if the type is not registered.

另請參閱 parameterCount (), parameterMetaType (), returnType ()，和 QMetaType .

[since 6.0] QByteArray QMetaMethod:: parameterTypeName ( int index ) const

Returns the name of the type at position index If there is no parameter at index , returns an empty QByteArray

該函數在 Qt 6.0 引入。

另請參閱 parameterNames ().

QList < QByteArray > QMetaMethod:: parameterTypes () const

Returns a list of parameter types.

另請參閱 parameterNames () 和 methodSignature ().

[since 6.0] int QMetaMethod:: relativeMethodIndex () const

Returns this method's local index inside.

該函數在 Qt 6.0 引入。

[since 6.0] QMetaType QMetaMethod:: returnMetaType () const

Returns the return type of this method.

該函數在 Qt 6.0 引入。

另請參閱 parameterMetaType (), QMetaType ，和 typeName ().

int QMetaMethod:: returnType () const

Returns the return type of this method.

The return value is one of the types that are registered with QMetaType ，或 QMetaType::UnknownType if the type is not registered.

另請參閱 parameterType (), QMetaType , typeName ()，和 returnMetaType ().

int QMetaMethod:: revision () const

Returns the method revision if one was specified by Q_REVISION , otherwise returns 0. Since Qt 6.0, non-zero values are encoded and can be decoded using QTypeRevision::fromEncodedVersion ().

const char *QMetaMethod:: tag () const

Returns the tag associated with this method.

Tags are special macros recognized by moc that make it possible to add extra information about a method.

Tag information can be added in the following way in the function declaration:

    // In the class MainWindow declaration
    #ifndef Q_MOC_RUN
    // define the tag text as empty, so the compiler doesn't see it
    #  define MY_CUSTOM_TAG
    #endif
    ...
    private slots:
        MY_CUSTOM_TAG void testFunc();
					

and the information can be accessed by using:

    MainWindow win;
    win.show();
    int functionIndex = win.metaObject()->indexOfSlot("testFunc()");
    QMetaMethod mm = win.metaObject()->method(functionIndex);
    qDebug() << mm.tag(); // prints MY_CUSTOM_TAG
					

For the moment, moc will extract and record all tags, but it will not handle any of them specially. You can use the tags to annotate your methods differently, and treat them according to the specific needs of your application.

注意： moc expands preprocessor macros, so it is necessary to surround the definition with #ifndef Q_MOC_RUN , as shown in the example above.

const char *QMetaMethod:: typeName () const

返迴此方法的返迴類型名稱。

另請參閱 returnType () 和 QMetaType::name ().

相關非成員

[noexcept] bool operator!= (const QMetaMethod & lhs , const QMetaMethod & rhs )

這是重載函數。

返迴 true 若方法 lhs 不等於方法 rhs ，否則返迴 false .

[noexcept] bool operator== (const QMetaMethod & lhs , const QMetaMethod & rhs )

這是重載函數。

返迴 true 若方法 lhs 等於方法 rhs ，否則返迴 false .

宏文檔編製

Q_METAMETHOD_INVOKE_MAX_ARGS

Equals maximum number of arguments available for execution of the method via QMetaMethod::invoke ()

內容

1. 公共類型

2. 公共函數

3. 靜態公共成員

4. 相關非成員

5. 宏

6. 詳細描述