Detailed Description

See also QMetaClassInfo, QMetaEnum, QMetaMethod, QMetaProperty, QMetaType, Meta-Object System

Returns true if the signal and method arguments are compatible; otherwise returns false.

Both signal and method are expected to be normalized.

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This is an overloaded function.

Returns true if the signal and method arguments are compatible; otherwise returns false.

This function was introduced in Qt 5.0.

Returns the meta-data for the item of class information with the given index.

Example:

class MyClass : public QObject
{
    Q_OBJECT
    Q_CLASSINFO("author", "Sabrina Schweinsteiger")
    Q_CLASSINFO("url", "http://doc.moosesoft.co.uk/1.0/")

public:
    ...
};

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Returns the number of items of class information in this class.

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Returns the class information offset for this class; i.e. the index position of this class's first class information item.

If the class has no superclasses with class information, the offset is 0; otherwise the offset is the sum of all the class information items in the class's superclasses.

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Returns the class name.

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Searches recursively for all child objects of the given object, and connects matching signals from them to slots of object that follow the following form:

void on_<object name>_<signal name>(<signal parameters>);

Let's assume our object has a child object of type QPushButton with the object name button1. The slot to catch the button's clicked() signal would be:

void on_button1_clicked();

If object itself has a properly set object name, its own signals are also connected to its respective slots.

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Returns the meta-data for the constructor with the given index.

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Returns the number of constructors in this class.

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Returns the meta-data for the enumerator with the given index.

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Returns the number of enumerators in this class.

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Returns the enumerator offset for this class; i.e. the index position of this class's first enumerator.

If the class has no superclasses with enumerators, the offset is 0; otherwise the offset is the sum of all the enumerators in the class's superclasses.

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Finds class information item name and returns its index; otherwise returns -1.

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Finds constructor and returns its index; otherwise returns -1.

Note that the constructor has to be in normalized form, as returned by normalizedSignature().

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Finds enumerator name and returns its index; otherwise returns -1.

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Finds method and returns its index; otherwise returns -1.

Note that the method has to be in normalized form, as returned by normalizedSignature().

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Finds property name and returns its index; otherwise returns -1.

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Finds signal and returns its index; otherwise returns -1.

This is the same as indexOfMethod(), except that it will return -1 if the method exists but isn't a signal.

Note that the signal has to be in normalized form, as returned by normalizedSignature().

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Finds slot and returns its index; otherwise returns -1.

This is the same as indexOfMethod(), except that it will return -1 if the method exists but isn't a slot.

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Returns true if the class described by this QMetaObject inherits the type described by metaObject; otherwise returns false.

A type is considered to inherit itself.

This function was introduced in Qt 5.7.

Invokes the member (a signal or a slot name) on the object obj. Returns true if the member could be invoked. Returns false if there is no such member or the parameters did not match.

The invocation can be either synchronous or asynchronous, depending on type:

• If type is Qt::DirectConnection, the member will be invoked immediately.

• If type is Qt::QueuedConnection, a QEvent will be sent and the member is invoked as soon as the application enters the main event loop.

• If 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.

• If 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.

The return value of the member function call is placed in ret. 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, and val9) to the member function.

QGenericArgument and QGenericReturnArgument are internal helper classes. Because signals and slots can be dynamically invoked, you must enclose the arguments using the Q_ARG() and Q_RETURN_ARG() macros. 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.

You only need to pass the name of the signal or slot to this function, not the entire signature. For example, to asynchronously invoke the quit() slot on a QThread, use the following code:

QMetaObject::invokeMethod(thread, "quit",
                          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

QMetaObject::invokeMethod: Unable to handle unregistered datatype 'MyType'

call qRegisterMetaType() to register the data type before you call invokeMethod().

To synchronously invoke the compute(QString, int, double) slot on some arbitrary object obj retrieve its return value:

QString retVal;
QMetaObject::invokeMethod(obj, "compute", Qt::DirectConnection,
                          Q_RETURN_ARG(QString, retVal),
                          Q_ARG(QString, "sqrt"),
                          Q_ARG(int, 42),
                          Q_ARG(double, 9.7));

If the "compute" slot does not take exactly one QString, one int and one double in the specified order, the call will fail.

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This function overloads invokeMethod().

This overload always invokes the member using the connection type Qt::AutoConnection.

This function overloads invokeMethod().

This overload can be used if the return value of the member is of no interest.

This function overloads invokeMethod().

This overload invokes the member using the connection type Qt::AutoConnection and ignores return values.

This is an overloaded function.

Invokes the function in the event loop of context. function can be a functor or a pointer to a member function. Returns true if the function could be invoked. Returns false if there is no such function or the parameters did not match. The return value of the function call is placed in ret.

This function was introduced in Qt 5.10.

This is an overloaded function.

Invokes the function in the event loop of context using the connection type Qt::AutoConnection. function can be a functor or a pointer to a member function. Returns true if the function could be invoked. Returns false if there is no such member or the parameters did not match. The return value of the function call is placed in ret.

This function was introduced in Qt 5.10.

Returns the metatype corresponding to this metaobject. If the metaobject originates from a namespace, an invalid metatype is returned.

This function was introduced in Qt 6.2.

Returns the meta-data for the method with the given index.

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Returns the number of methods in this class, including the number of methods provided by each base class. These include signals and slots as well as normal member functions.

Use code like the following to obtain a QStringList containing the methods specific to a given class:

const QMetaObject* metaObject = obj->metaObject();
QStringList methods;
for(int i = metaObject->methodOffset(); i < metaObject->methodCount(); ++i)
    methods << QString::fromLatin1(metaObject->method(i).methodSignature());

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Returns the method offset for this class; i.e. the index position of this class's first member function.

The offset is the sum of all the methods in the class's superclasses (which is always positive since QObject has the deleteLater() slot and a destroyed() signal).

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Constructs a new instance of this class. You can pass up to ten arguments (val0, val1, val2, val3, val4, val5, val6, val7, val8, and val9) to the constructor. Returns the new object, or nullptr if no suitable constructor is available.

Note that only constructors that are declared with the Q_INVOKABLE modifier are made available through the meta-object system.

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Normalizes the signature of the given method.

Qt uses normalized signatures to decide whether two given signals and slots are compatible. Normalization reduces whitespace to a minimum, moves 'const' to the front where appropriate, removes 'const' from value types and replaces const references with values.

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Normalizes a type.

See QMetaObject::normalizedSignature() for a description on how Qt normalizes.

Example:

QByteArray normType = QMetaObject::normalizedType(" int    const  *");
// normType is now "const int*"

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Returns the meta-data for the property with the given index. If no such property exists, a null QMetaProperty is returned.

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Returns the number of properties in this class, including the number of properties provided by each base class.

Use code like the following to obtain a QStringList containing the properties specific to a given class:

const QMetaObject* metaObject = obj->metaObject();
QStringList properties;
for(int i = metaObject->propertyOffset(); i < metaObject->propertyCount(); ++i)
    properties << QString::fromLatin1(metaObject->property(i).name());

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Returns the property offset for this class; i.e. the index position of this class's first property.

The offset is the sum of all the properties in the class's superclasses (which is always positive since QObject has the name() property).

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Returns the meta-object of the superclass, or nullptr if there is no such object.

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Returns the property that has the USER flag set to true.

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This macro takes a Type and a value of that type and returns a QGenericArgument object that can be passed to QMetaObject::invokeMethod().

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This macro takes a Type and a non-const reference to a value of that type and returns a QGenericReturnArgument object that can be passed to QMetaObject::invokeMethod().

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