QMetaMethod

The QMetaMethod class provides meta-data about a member function. More…

Inheritance diagram of PySide2.QtCore.QMetaMethod

Synopsis

Functions

  • def __eq__ (, m2)

  • def __ne__ (, m2)

  • def access ()

  • def enclosingMetaObject ()

  • def invoke (object, connectionType, returnValue[, val0=QGenericArgument(nullptr)[, val1=QGenericArgument()[, val2=QGenericArgument()[, val3=QGenericArgument()[, val4=QGenericArgument()[, val5=QGenericArgument()[, val6=QGenericArgument()[, val7=QGenericArgument()[, val8=QGenericArgument()[, val9=QGenericArgument()]]]]]]]]]])

  • def invoke (object, connectionType[, val0=QGenericArgument(nullptr)[, val1=QGenericArgument()[, val2=QGenericArgument()[, val3=QGenericArgument()[, val4=QGenericArgument()[, val5=QGenericArgument()[, val6=QGenericArgument()[, val7=QGenericArgument()[, val8=QGenericArgument()[, val9=QGenericArgument()]]]]]]]]]])

  • def invoke (object, returnValue[, val0=QGenericArgument(nullptr)[, val1=QGenericArgument()[, val2=QGenericArgument()[, val3=QGenericArgument()[, val4=QGenericArgument()[, val5=QGenericArgument()[, val6=QGenericArgument()[, val7=QGenericArgument()[, val8=QGenericArgument()[, val9=QGenericArgument()]]]]]]]]]])

  • def invoke (object[, val0=QGenericArgument(nullptr)[, val1=QGenericArgument()[, val2=QGenericArgument()[, val3=QGenericArgument()[, val4=QGenericArgument()[, val5=QGenericArgument()[, val6=QGenericArgument()[, val7=QGenericArgument()[, val8=QGenericArgument()[, val9=QGenericArgument()]]]]]]]]]])

  • def invokeOnGadget (gadget, returnValue[, val0=QGenericArgument(nullptr)[, val1=QGenericArgument()[, val2=QGenericArgument()[, val3=QGenericArgument()[, val4=QGenericArgument()[, val5=QGenericArgument()[, val6=QGenericArgument()[, val7=QGenericArgument()[, val8=QGenericArgument()[, val9=QGenericArgument()]]]]]]]]]])

  • def invokeOnGadget (gadget[, val0=QGenericArgument(nullptr)[, val1=QGenericArgument()[, val2=QGenericArgument()[, val3=QGenericArgument()[, val4=QGenericArgument()[, val5=QGenericArgument()[, val6=QGenericArgument()[, val7=QGenericArgument()[, val8=QGenericArgument()[, val9=QGenericArgument()]]]]]]]]]])

  • def isValid ()

  • def methodIndex ()

  • def methodSignature ()

  • def methodType ()

  • def name ()

  • def parameterCount ()

  • def parameterNames ()

  • def parameterType (index)

  • def parameterTypes ()

  • def returnType ()

  • def revision ()

  • def tag ()

  • def typeName ()

Detailed Description

A QMetaMethod has a methodType() , a methodSignature() , a list of parameterTypes() and parameterNames() , a return typeName() , a tag() , and an access() specifier. You can use invoke() to invoke the method on an arbitrary QObject .

See also

QMetaObject QMetaEnum QMetaProperty Qt’s Property System

class PySide2.QtCore.QMetaMethod

PySide2.QtCore.QMetaMethod(QMetaMethod)

Parameters:

QMetaMethod – PySide2.QtCore.QMetaMethod

PySide2.QtCore.QMetaMethod.Access

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

Constant

Description

QMetaMethod.Private

QMetaMethod.Protected

QMetaMethod.Public
PySide2.QtCore.QMetaMethod.MethodType

Constant

Description

QMetaMethod.Method

The function is a plain member function.

QMetaMethod.Signal

The function is a signal.

QMetaMethod.Slot

The function is a slot.

QMetaMethod.Constructor

The function is a constructor.
PySide2.QtCore.QMetaMethod.access()
Return type:

Access

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

Note

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.

See also

methodType()

PySide2.QtCore.QMetaMethod.enclosingMetaObject()
Return type:

PySide2.QtCore.QMetaObject

PySide2.QtCore.QMetaMethod.invoke(object[, val0=QGenericArgument(nullptr)[, val1=QGenericArgument()[, val2=QGenericArgument()[, val3=QGenericArgument()[, val4=QGenericArgument()[, val5=QGenericArgument()[, val6=QGenericArgument()[, val7=QGenericArgument()[, val8=QGenericArgument()[, val9=QGenericArgument()]]]]]]]]]])
Parameters:
Return type:

bool

This function overloads invoke() .

This overload invokes this method using the connection type AutoConnection and ignores return values.

PySide2.QtCore.QMetaMethod.invoke(object, returnValue[, val0=QGenericArgument(nullptr)[, val1=QGenericArgument()[, val2=QGenericArgument()[, val3=QGenericArgument()[, val4=QGenericArgument()[, val5=QGenericArgument()[, val6=QGenericArgument()[, val7=QGenericArgument()[, val8=QGenericArgument()[, val9=QGenericArgument()]]]]]]]]]])
Parameters:
Return type:

bool

This function overloads invoke() .

This overload always invokes this method using the connection type AutoConnection .

PySide2.QtCore.QMetaMethod.invoke(object, connectionType[, val0=QGenericArgument(nullptr)[, val1=QGenericArgument()[, val2=QGenericArgument()[, val3=QGenericArgument()[, val4=QGenericArgument()[, val5=QGenericArgument()[, val6=QGenericArgument()[, val7=QGenericArgument()[, val8=QGenericArgument()[, val9=QGenericArgument()]]]]]]]]]])
Parameters:
Return type:

bool

This function overloads invoke() .

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

PySide2.QtCore.QMetaMethod.invoke(object, connectionType, returnValue[, val0=QGenericArgument(nullptr)[, val1=QGenericArgument()[, val2=QGenericArgument()[, val3=QGenericArgument()[, val4=QGenericArgument()[, val5=QGenericArgument()[, val6=QGenericArgument()[, val7=QGenericArgument()[, val8=QGenericArgument()[, val9=QGenericArgument()]]]]]]]]]])
Parameters:
Return type:

bool

Invokes this method on the object object . 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 the connectionType :

  • If connectionType is DirectConnection , the member will be invoked immediately.

  • If connectionType is QueuedConnection , a QEvent will be posted and the member is invoked as soon as the application enters the main event loop.

  • If connectionType is AutoConnection , the member is invoked synchronously if object lives in the same thread as the caller; otherwise it will invoke the member asynchronously.

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 , and 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() 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.

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

methodIndex = pushButton.metaObject().indexOfMethod("animateClick()")
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 .

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

retVal = QString()
normalizedSignature = QMetaObject.normalizedSignature("compute(QString, int, double)")
methodIndex = obj.metaObject().indexOfMethod(normalizedSignature)
method = 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));

normalizedSignature() is used here to ensure that the format of the signature is what expects. E.g. extra whitespace is removed.

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

Warning

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.

See also

Q_ARG() Q_RETURN_ARG() qRegisterMetaType() invokeMethod()

PySide2.QtCore.QMetaMethod.invokeOnGadget(gadget[, val0=QGenericArgument(nullptr)[, val1=QGenericArgument()[, val2=QGenericArgument()[, val3=QGenericArgument()[, val4=QGenericArgument()[, val5=QGenericArgument()[, val6=QGenericArgument()[, val7=QGenericArgument()[, val8=QGenericArgument()[, val9=QGenericArgument()]]]]]]]]]])
Parameters:
Return type:

bool

This is an overloaded function.

This overload invokes this method for a gadget and ignores return values.

PySide2.QtCore.QMetaMethod.invokeOnGadget(gadget, returnValue[, val0=QGenericArgument(nullptr)[, val1=QGenericArgument()[, val2=QGenericArgument()[, val3=QGenericArgument()[, val4=QGenericArgument()[, val5=QGenericArgument()[, val6=QGenericArgument()[, val7=QGenericArgument()[, val8=QGenericArgument()[, val9=QGenericArgument()]]]]]]]]]])
Parameters:
Return type:

bool

Invokes this method on a Q_GADGET . Returns true if the member could be invoked. Returns false if there is no such member or the parameters did not match.

The pointer gadget must point to an instance of the gadget class.

The invocation is always synchronous.

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 , and val9 ) to this method call.

Warning

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.

See also

Q_ARG() Q_RETURN_ARG() qRegisterMetaType() invokeMethod()

PySide2.QtCore.QMetaMethod.isValid()
Return type:

bool

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

PySide2.QtCore.QMetaMethod.methodIndex()
Return type:

int

Returns this method’s index.

PySide2.QtCore.QMetaMethod.methodSignature()
Return type:

PySide2.QtCore.QByteArray

Returns the signature of this method (e.g., setValue(double) ).

See also

parameterTypes() parameterNames()

PySide2.QtCore.QMetaMethod.methodType()
Return type:

MethodType

Returns the type of this method (signal, slot, or method).

See also

access()

PySide2.QtCore.QMetaMethod.name()
Return type:

PySide2.QtCore.QByteArray

Returns the name of this method.

See also

methodSignature() parameterCount()

PySide2.QtCore.QMetaMethod.__ne__(m2)
Parameters:

m2 – PySide2.QtCore.QMetaMethod

Return type:

bool

PySide2.QtCore.QMetaMethod.__eq__(m2)
Parameters:

m2 – PySide2.QtCore.QMetaMethod

Return type:

bool

PySide2.QtCore.QMetaMethod.parameterCount()
Return type:

int

Returns the number of parameters of this method.

See also

parameterType() parameterNames()

PySide2.QtCore.QMetaMethod.parameterNames()
Return type:

Returns a list of parameter names.

See also

parameterTypes() methodSignature()

PySide2.QtCore.QMetaMethod.parameterType(index)
Parameters:

index – int

Return type:

int

Returns the type of the parameter at the given index .

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

See also

parameterCount() returnType() QMetaType

PySide2.QtCore.QMetaMethod.parameterTypes()
Return type:

Returns a list of parameter types.

See also

parameterNames() methodSignature()

PySide2.QtCore.QMetaMethod.returnType()
Return type:

int

Returns the return type of this method.

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

See also

parameterType() QMetaType typeName()

PySide2.QtCore.QMetaMethod.revision()
Return type:

int

Returns the method revision if one was specified by Q_REVISION , otherwise returns 0.

PySide2.QtCore.QMetaMethod.tag()
Return type:

str

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.

Note

Since Qt 5.0, 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.

PySide2.QtCore.QMetaMethod.typeName()
Return type:

str

Returns the return type name of this method.

See also

returnType() type()