QMetaMethod 类提供有关成员函数的元数据。 更多...
| 头： | #include <QMetaMethod> |
| CMake: |
find_package(Qt6 COMPONENTS Core REQUIRED)
target_link_libraries(mytarget PRIVATE Qt6::Core) |
| qmake: | QT += core |
| enum | Access { Private, Protected, Public } |
| enum | MethodType { Method, Signal, Slot, Constructor } |
| QMetaMethod::Access | access () const |
| bool | invoke (QObject * object , Qt::ConnectionType connectionType , QGenericReturnArgument returnValue , QGenericArgument val0 = QGenericArgument(nullptr), QGenericArgument val1 = QGenericArgument(), QGenericArgument val2 = QGenericArgument(), QGenericArgument val3 = QGenericArgument(), QGenericArgument val4 = QGenericArgument(), QGenericArgument val5 = QGenericArgument(), QGenericArgument val6 = QGenericArgument(), QGenericArgument val7 = QGenericArgument(), QGenericArgument val8 = QGenericArgument(), QGenericArgument val9 = QGenericArgument()) const |
| bool | invoke (QObject * object , QGenericReturnArgument returnValue , QGenericArgument val0 = QGenericArgument(0), QGenericArgument val1 = QGenericArgument(), QGenericArgument val2 = QGenericArgument(), QGenericArgument val3 = QGenericArgument(), QGenericArgument val4 = QGenericArgument(), QGenericArgument val5 = QGenericArgument(), QGenericArgument val6 = QGenericArgument(), QGenericArgument val7 = QGenericArgument(), QGenericArgument val8 = QGenericArgument(), QGenericArgument val9 = QGenericArgument()) const |
| bool | invoke (QObject * object , Qt::ConnectionType connectionType , QGenericArgument val0 = QGenericArgument(0), QGenericArgument val1 = QGenericArgument(), QGenericArgument val2 = QGenericArgument(), QGenericArgument val3 = QGenericArgument(), QGenericArgument val4 = QGenericArgument(), QGenericArgument val5 = QGenericArgument(), QGenericArgument val6 = QGenericArgument(), QGenericArgument val7 = QGenericArgument(), QGenericArgument val8 = QGenericArgument(), QGenericArgument val9 = QGenericArgument()) const |
| bool | invoke (QObject * object , QGenericArgument val0 = QGenericArgument(0), QGenericArgument val1 = QGenericArgument(), QGenericArgument val2 = QGenericArgument(), QGenericArgument val3 = QGenericArgument(), QGenericArgument val4 = QGenericArgument(), QGenericArgument val5 = QGenericArgument(), QGenericArgument val6 = QGenericArgument(), QGenericArgument val7 = QGenericArgument(), QGenericArgument val8 = QGenericArgument(), QGenericArgument val9 = QGenericArgument()) const |
| bool | invokeOnGadget (void * gadget , QGenericReturnArgument returnValue , QGenericArgument val0 = QGenericArgument(nullptr), QGenericArgument val1 = QGenericArgument(), QGenericArgument val2 = QGenericArgument(), QGenericArgument val3 = QGenericArgument(), QGenericArgument val4 = QGenericArgument(), QGenericArgument val5 = QGenericArgument(), QGenericArgument val6 = QGenericArgument(), QGenericArgument val7 = QGenericArgument(), QGenericArgument val8 = QGenericArgument(), QGenericArgument val9 = QGenericArgument()) const |
| bool | invokeOnGadget (void * gadget , QGenericArgument val0 = QGenericArgument(0), QGenericArgument val1 = QGenericArgument(), QGenericArgument val2 = QGenericArgument(), QGenericArgument val3 = QGenericArgument(), QGenericArgument val4 = QGenericArgument(), QGenericArgument val5 = QGenericArgument(), QGenericArgument val6 = QGenericArgument(), QGenericArgument val7 = QGenericArgument(), QGenericArgument val8 = QGenericArgument(), QGenericArgument val9 = QGenericArgument()) const |
| bool | isConst () const |
| bool | isValid () const |
| int | methodIndex () const |
| QByteArray | methodSignature () const |
| QMetaMethod::MethodType | methodType () const |
| QByteArray | name () const |
| int | parameterCount () const |
| QMetaType | parameterMetaType (int index ) const |
| QList<QByteArray> | parameterNames () const |
| int | parameterType (int index ) const |
| QByteArray | parameterTypeName (int index ) const |
| QList<QByteArray> | parameterTypes () const |
| int | relativeMethodIndex () const |
| QMetaType | returnMetaType () const |
| int | returnType () const |
| int | revision () const |
| const char * | tag () const |
| const char * | typeName () const |
| QMetaMethod | fromSignal (PointerToMemberFunction signal ) |
| bool | operator!= (const QMetaMethod & m1 , const QMetaMethod & m2 ) |
| bool | operator== (const QMetaMethod & m1 , const QMetaMethod & m2 ) |
| Q_METAMETHOD_INVOKE_MAX_ARGS |
QMetaMethod 拥有 methodType ()， methodSignature (), 列表化的 parameterTypes () 和 parameterNames (), a return typeName ()， tag (), and an access () specifier. You can use invoke () to invoke the method on an arbitrary QObject .
另请参阅 QMetaObject , QMetaEnum , QMetaProperty ，和 Qt 的特性系统 .
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
|
| 常量 | 值 | 描述 |
|---|---|---|
QMetaMethod::Method
|
0
|
函数是纯成员函数。 |
QMetaMethod::Signal
|
1
|
函数是信号。 |
QMetaMethod::Slot
|
2
|
函数是槽。 |
QMetaMethod::Constructor
|
3
|
函数是构造函数。 |
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.
另请参阅 methodType ().
[static, since 5.0]
template <typename PointerToMemberFunction>
QMetaMethod
QMetaMethod::
fromSignal
(
PointerToMemberFunction
signal
)
返回的元方法相当于给定 signal ，或无效 QMetaMethod if signal 不是类的信号。
范例：
QMetaMethod destroyedSignal = QMetaMethod::fromSignal(&QObject::destroyed);
该函数在 Qt 5.0 引入。
Invokes this method on the object
object
。返回
true
若成员可以被援引。返回
false
若没有这样的成员或参数不匹配。
The invocation can be either synchronous or asynchronous, depending on the connectionType :
The return value of this method call is placed in returnValue . If the invocation is asynchronous, the return value cannot be evaluated. You can pass up to ten arguments ( val0 , val1 , val2 , val3 , val4 , val5 , val6 , val7 , val8 ，和 val9 ) to this method call.
QGenericArgument and QGenericReturnArgument are internal helper classes. Because signals and slots can be dynamically invoked, you must enclose the arguments using the Q_ARG () 和 Q_RETURN_ARG () 宏。 Q_ARG () takes a type name and a const reference of that type; Q_RETURN_ARG () takes a type name and a non-const reference.
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 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
QMetaMethod::invoke: Unable to handle unregistered datatype 'MyType'
call qRegisterMetaType () to register the data type before you call QMetaMethod::invoke().
要同步援引
compute(QString, int, double)
slot on some arbitrary object
obj
检索其返回值：
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, Q_RETURN_ARG(QString, retVal), Q_ARG(QString, "sqrt"), Q_ARG(int, 42), Q_ARG(double, 9.7));
QMetaObject::normalizedSignature () is used here to ensure that the format of the signature is what invoke() expects. E.g. extra whitespace is removed.
若 compute 槽不接受恰好一个 QString , one int and one double in the specified order, the call will fail.
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. The arguments must have the same type as the ones expected by the method, else, the behaviour is undefined.
另请参阅 Q_ARG (), Q_RETURN_ARG (), qRegisterMetaType ()，和 QMetaObject::invokeMethod ().
This function overloads invoke().
This overload always invokes this method using the connection type Qt::AutoConnection .
This function overloads invoke().
此重载可以被使用，若对成员的返回值不感兴趣。
This function overloads invoke().
This overload invokes this method using the connection type Qt::AutoConnection 并忽略返回值。
[since 5.5]
bool
QMetaMethod::
invokeOnGadget
(
void
*
gadget
,
QGenericReturnArgument
returnValue
,
QGenericArgument
val0
= QGenericArgument(nullptr),
QGenericArgument
val1
= QGenericArgument(),
QGenericArgument
val2
= QGenericArgument(),
QGenericArgument
val3
= QGenericArgument(),
QGenericArgument
val4
= QGenericArgument(),
QGenericArgument
val5
= QGenericArgument(),
QGenericArgument
val6
= QGenericArgument(),
QGenericArgument
val7
= QGenericArgument(),
QGenericArgument
val8
= QGenericArgument(),
QGenericArgument
val9
= QGenericArgument()) const
Invokes this method on a
Q_GADGET
。返回
true
若成员可以被援引。返回
false
若没有这样的成员或参数不匹配。
指针 gadget must point to an instance of the gadget class.
援引始终是同步的。
The return value of this method call is placed in returnValue . You can pass up to ten arguments ( val0 , val1 , val2 , val3 , val4 , val5 , val6 , val7 , val8 ，和 val9 ) to this method call.
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. The arguments must have the same type as the ones expected by the method, else, the behavior is undefined.
该函数在 Qt 5.5 引入。
另请参阅 Q_ARG (), Q_RETURN_ARG (), qRegisterMetaType ()，和 QMetaObject::invokeMethod ().
[since 5.5]
bool
QMetaMethod::
invokeOnGadget
(
void
*
gadget
,
QGenericArgument
val0
= QGenericArgument(0),
QGenericArgument
val1
= QGenericArgument(),
QGenericArgument
val2
= QGenericArgument(),
QGenericArgument
val3
= QGenericArgument(),
QGenericArgument
val4
= QGenericArgument(),
QGenericArgument
val5
= QGenericArgument(),
QGenericArgument
val6
= QGenericArgument(),
QGenericArgument
val7
= QGenericArgument(),
QGenericArgument
val8
= QGenericArgument(),
QGenericArgument
val9
= QGenericArgument()) const
这是重载函数。
这重载援引此方法为 gadget 并忽略返回值。
该函数在 Qt 5.5 引入。
[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.
该函数在 Qt 6.2 引入。
[since 5.0]
bool
QMetaMethod::
isValid
() const
返回
true
if this method is valid (can be introspected and invoked), otherwise returns
false
.
该函数在 Qt 5.0 引入。
返回此方法的索引。
[since 5.0]
QByteArray
QMetaMethod::
methodSignature
() const
返回此方法的签名 (如
setValue(double)
).
该函数在 Qt 5.0 引入。
另请参阅 parameterTypes () 和 parameterNames ().
返回此方法 (信号、槽或方法) 的类型。
另请参阅 access ().
[since 5.0]
QByteArray
QMetaMethod::
name
() const
返回此方法的名称。
该函数在 Qt 5.0 引入。
另请参阅 methodSignature () 和 parameterCount ().
[since 5.0]
int
QMetaMethod::
parameterCount
() const
返回此方法的参数数。
该函数在 Qt 5.0 引入。
另请参阅 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 被返回。
该函数在 Qt 6.0 引入。
另请参阅 parameterCount (), returnMetaType ()，和 QMetaType .
返回参数名称的列表。
另请参阅 parameterTypes () 和 methodSignature ().
[since 5.0]
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.
该函数在 Qt 5.0 引入。
另请参阅 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
该函数在 Qt 6.0 引入。
另请参阅 parameterNames ().
Returns a list of parameter types.
另请参阅 parameterNames () 和 methodSignature ().
[since 6.0]
int
QMetaMethod::
relativeMethodIndex
() const
Returns this method's local index inside.
该函数在 Qt 6.0 引入。
[since 6.0]
QMetaType
QMetaMethod::
returnMetaType
() const
Returns the return type of this method.
该函数在 Qt 6.0 引入。
另请参阅 parameterMetaType (), QMetaType ，和 typeName ().
[since 5.0]
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.
该函数在 Qt 5.0 引入。
另请参阅 parameterType (), QMetaType , typeName ()，和 returnMetaType ().
[since 5.1]
int
QMetaMethod::
revision
() const
Returns the method revision if one was specified by Q_REVISION , otherwise returns 0.
该函数在 Qt 5.1 引入。
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：
从 Qt 5.0 起，
moc
expands preprocessor macros, so it is necessary to surround the definition with
#ifndef
Q_MOC_RUN
, as shown in the example above. This was not required in Qt 4. The code as shown above works with Qt 4 too.
返回此方法的返回类型名称。
另请参阅 returnType () 和 QMetaType::type ().
[since 5.0]
bool
operator!=
(const
QMetaMethod
&
m1
, const
QMetaMethod
&
m2
)
这是重载函数。
返回
true
若方法
m1
不等于方法
m2
，否则返回
false
.
该函数在 Qt 5.0 引入。
[since 5.0]
bool
operator==
(const
QMetaMethod
&
m1
, const
QMetaMethod
&
m2
)
这是重载函数。
返回
true
若方法
m1
等于方法
m2
，否则返回
false
.
该函数在 Qt 5.0 引入。
Equals maximum number of arguments available for execution of the method via QMetaMethod::invoke ()