QMetaMethod Class Reference
[QtCore module]
The QMetaMethod class provides meta-data about a member
function. More...
Types
- enum Access { Private, Protected, Public }
- enum MethodType { Method, Signal, Slot, Constructor }
Methods
- __init__ (self)
- __init__ (self, QMetaMethod)
- Access access (self)
- object invoke (self, QObject object, Qt.ConnectionType connectionType, QGenericReturnArgument returnValue, QGenericArgument value0 = QGenericArgument(0,0), QGenericArgument value1 = QGenericArgument(0,0), QGenericArgument value2 = QGenericArgument(0,0), QGenericArgument value3 = QGenericArgument(0,0), QGenericArgument value4 = QGenericArgument(0,0), QGenericArgument value5 = QGenericArgument(0,0), QGenericArgument value6 = QGenericArgument(0,0), QGenericArgument value7 = QGenericArgument(0,0), QGenericArgument value8 = QGenericArgument(0,0), QGenericArgument value9 = QGenericArgument(0,0))
- object invoke (self, QObject object, QGenericReturnArgument returnValue, QGenericArgument value0 = QGenericArgument(0,0), QGenericArgument value1 = QGenericArgument(0,0), QGenericArgument value2 = QGenericArgument(0,0), QGenericArgument value3 = QGenericArgument(0,0), QGenericArgument value4 = QGenericArgument(0,0), QGenericArgument value5 = QGenericArgument(0,0), QGenericArgument value6 = QGenericArgument(0,0), QGenericArgument value7 = QGenericArgument(0,0), QGenericArgument value8 = QGenericArgument(0,0), QGenericArgument value9 = QGenericArgument(0,0))
- object invoke (self, QObject object, Qt.ConnectionType connectionType, QGenericArgument value0 = QGenericArgument(0,0), QGenericArgument value1 = QGenericArgument(0,0), QGenericArgument value2 = QGenericArgument(0,0), QGenericArgument value3 = QGenericArgument(0,0), QGenericArgument value4 = QGenericArgument(0,0), QGenericArgument value5 = QGenericArgument(0,0), QGenericArgument value6 = QGenericArgument(0,0), QGenericArgument value7 = QGenericArgument(0,0), QGenericArgument value8 = QGenericArgument(0,0), QGenericArgument value9 = QGenericArgument(0,0))
- object invoke (self, QObject object, QGenericArgument value0 = QGenericArgument(0,0), QGenericArgument value1 = QGenericArgument(0,0), QGenericArgument value2 = QGenericArgument(0,0), QGenericArgument value3 = QGenericArgument(0,0), QGenericArgument value4 = QGenericArgument(0,0), QGenericArgument value5 = QGenericArgument(0,0), QGenericArgument value6 = QGenericArgument(0,0), QGenericArgument value7 = QGenericArgument(0,0), QGenericArgument value8 = QGenericArgument(0,0), QGenericArgument value9 = QGenericArgument(0,0))
- int methodIndex (self)
- MethodType methodType (self)
- list-of-QByteArray parameterNames (self)
- list-of-QByteArray parameterTypes (self)
- str signature (self)
- str tag (self)
- str typeName (self)
Detailed Description
The QMetaMethod class provides meta-data about a member
function.
A QMetaMethod has a methodType(), a signature(), 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.
Type Documentation
QMetaMethod.Access
This enum describes the access level of a method, following the
conventions used in C++.
Constant |
Value |
QMetaMethod.Private |
0 |
QMetaMethod.Protected |
1 |
QMetaMethod.Public |
2 |
QMetaMethod.MethodType
|
Constant |
Value |
Description |
QMetaMethod.Method |
0 |
The function is a plain member function. |
QMetaMethod.Signal |
1 |
The function is a signal. |
QMetaMethod.Slot |
2 |
The function is a slot. |
QMetaMethod.Constructor |
3 |
The function is a constructor. |
Method Documentation
QMetaMethod.__init__ (self)
QMetaMethod.__init__ (self, QMetaMethod)
Access QMetaMethod.access (self)
Returns the access specification of this method (private,
protected, or public).
Signals are always protected, meaning that you can only emit
them from the class or from a subclass.
See also methodType().
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 Qt.DirectConnection, the member
will be invoked immediately.
- If connectionType is Qt.QueuedConnection, a QEvent will be posted and the member is invoked
as soon as the application enters the main event loop.
- If connectionType is Qt.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:
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().
To synchronously invoke the compute(QString, int,
double) slot on some arbitrary object obj retrieve
its return value:
QString retVal;
QByteArray normalizedSignature = QMetaObject.normalizedSignature("compute(QString, int, double)");
int methodIndex = obj->metaObject()->indexOfMethod(normalizedSignature);
QMetaMethod 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));
QMetaObject.normalizedSignature()
is used here to ensure that the format of the signature is what
invoke() 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(), and
QMetaObject.invokeMethod().
object QMetaMethod.invoke (self, QObject object, QGenericReturnArgument returnValue, QGenericArgument value0 = QGenericArgument(0,0), QGenericArgument value1 = QGenericArgument(0,0), QGenericArgument value2 = QGenericArgument(0,0), QGenericArgument value3 = QGenericArgument(0,0), QGenericArgument value4 = QGenericArgument(0,0), QGenericArgument value5 = QGenericArgument(0,0), QGenericArgument value6 = QGenericArgument(0,0), QGenericArgument value7 = QGenericArgument(0,0), QGenericArgument value8 = QGenericArgument(0,0), QGenericArgument value9 = QGenericArgument(0,0))
This function overloads invoke().
This overload always invokes this method using the connection
type Qt.AutoConnection.
object QMetaMethod.invoke (self, QObject object, Qt.ConnectionType connectionType, QGenericArgument value0 = QGenericArgument(0,0), QGenericArgument value1 = QGenericArgument(0,0), QGenericArgument value2 = QGenericArgument(0,0), QGenericArgument value3 = QGenericArgument(0,0), QGenericArgument value4 = QGenericArgument(0,0), QGenericArgument value5 = QGenericArgument(0,0), QGenericArgument value6 = QGenericArgument(0,0), QGenericArgument value7 = QGenericArgument(0,0), QGenericArgument value8 = QGenericArgument(0,0), QGenericArgument value9 = QGenericArgument(0,0))
This function overloads invoke().
This overload can be used if the return value of the member is
of no interest.
object QMetaMethod.invoke (self, QObject object, QGenericArgument value0 = QGenericArgument(0,0), QGenericArgument value1 = QGenericArgument(0,0), QGenericArgument value2 = QGenericArgument(0,0), QGenericArgument value3 = QGenericArgument(0,0), QGenericArgument value4 = QGenericArgument(0,0), QGenericArgument value5 = QGenericArgument(0,0), QGenericArgument value6 = QGenericArgument(0,0), QGenericArgument value7 = QGenericArgument(0,0), QGenericArgument value8 = QGenericArgument(0,0), QGenericArgument value9 = QGenericArgument(0,0))
This function overloads invoke().
This overload invokes this method using the connection type
Qt.AutoConnection and
ignores return values.
int QMetaMethod.methodIndex (self)
Returns this method's index.
This function was introduced in Qt 4.6.
MethodType QMetaMethod.methodType (self)
Returns the type of this method (signal, slot, or method).
See also access().
list-of-QByteArray QMetaMethod.parameterNames (self)
Returns a list of parameter names.
See also parameterTypes() and signature().
list-of-QByteArray QMetaMethod.parameterTypes (self)
Returns a list of parameter types.
See also parameterNames() and signature().
str QMetaMethod.signature (self)
Returns the signature of this method (e.g.,
setValue(double)).
See also parameterTypes() and parameterNames().
str QMetaMethod.tag (self)
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. For the moment,
moc doesn't support any special tags.
str QMetaMethod.typeName (self)
Returns the return type of this method, or an empty string if
the return type is void.