bool QAbstractItemModel:: insertColumn ( int column, const QModelIndex & parent = QModelIndex ()) Inserts a single column before the given column in the child items of the parent specified. ", which suggests it is only for classes and structs. It seems that for a metatype that is a QList<MyClass::MyEnum> I must. No, everything is in separated folders. connect(self. ) The image I am trying to pass is a cv::Mat which I converted to a QImage which I afterwards converted to a QString. Maybe qRegisterMetaType is what you missed. Otherwise you might be adding duplicate entries to the metatype database each time. call qRegisterMetaType() to register the data type before you call QMetaMethod::invoke(). ", which suggests it is only for classes and structs. But with the shared_ptr object, not a pointer to the shared pointer! You will have to register std::shared_ptr<yourclass> with the Qt meta object system before this can work, i. You need to create your own factory that will register functors that will call qRegisterMetaType in runtime. QTextCharFormat. the type name must be specified without the class, as in. There's no compile time error, but when I run. So in both cases qRegisterMetaType isn't required for the slot to be called and the custom type to be accessible within the slot (i. ) Run a loop on your C++ list and call the append function of qml to add all that data into qml list as well. ) From what I've read, this should totally work. I have no problem with registering and using C++ enums in QML code. ) このような場合は以下の通り qRegisterMetaType() の引数を設定することで回避できることがある。You can safely remove the const, even if the real signature of SendData and ReceiveData is const u_char*. can include digits and underscore). QMetaType is Qt's way to have run-time dynamic information about your types. Compares the objects at lhs and rhsfor ordering. 因为没有指定 connect的链接方向 Qt::DirectConnection. QVariants are important in QML because they used to store the arguments from signals and slots, and also get values from the QMetaProperty system. Note: it's also safe to call qRegisterMetaType () multiple times. 11. ) 1 stopped. The following code will work similarly: using namespace foo; qRegisterMetaType<MyClass> ("MyClass"); qRegisterMetaType<MyClass> ("foo::MyClass"); For example, the "MyClass" and "foo::MyClass" strings are used to identify argument types when you refer to your signals and slots. 2D Graphics #. My first intuition was to have a class inheriting from rclcpp::Node only with an instance of MainWindow but didn't manage to have it work that way. In this case the slot is executed as a normal function call. M. Qt documentation specifically states that qRegisterMetaType<T>() must be called for a type to work in the Qt property system. We have two classes in this example: DataGeneratorThread: is a QThread and is responsible for the actual data generation (generates random numbers according to a gaussian p. MainWindow win; win. But Q_OBJECT macro handles this automatically. The type and its values must start with a capital letter but otherwise follow rules for naming a variable (e. But the problem comes up when I try to send it to C++ slot, that have my enum as parameter. emit (statuses) Share. You have to register your custom type for queued signals because by registering it, Qt can make a copy of it in its event loop (which certainly uses QVariant) and pass it as argument later (when the original passed value is long since out. Now, this simple class holds small samples of. 0’ of a module called ‘com. qRegisterMetaType<MyStruct>("MyStruct"); 若已经使用 Q_DECLARE_METATYPEQ 标记过该类型，可以使用其不带参数的版本： qRegisterMetaType<MyStruct>(); 同样的，若对象包含在自定义的命名空间中时，注册时要带上完整的命令空间，如： qRegisterMetaType<NSP::MyStruct>("NSP::MyStruct"); Note that for enum types, you no not even need to call qRegisterMetaType () in these cases. Share. 048771190]: Out drawPath [ INFO] [1432901455. Step 2 (meta type Declare macro), if needed, describe your custom type/class to things like QVariant, QDebug and other "support" systems used everywhere on QObjects. 0 and have problems registering my own class as a QMetaType. g. I created a. See also disconnect(), sender(), qRegisterMetaType(), Q_DECLARE_METATYPE(), and Differences between String-Based and Functor-Based Connections. QtCore import * from PyQt5. hEvaluating Scripts. [quote author="Andre" date="1306394817"]In that case, I think you need to register them. 我们知道类中的成员函数并不一定会被调用 (即，该宏并不确保类型被注册到MetaType)。. Section and Key Syntax. 用qRegisterMetaType对自定义的类型进行注册，就是为了告诉Qt如何去做这些事情。. . h #pragma once #include <QThread>. QWaitCondition allows a thread to tell other threads that some sort of condition has been met. Any class or struct that has a public default constructor, a public copy constructor, and a public destructor can be registered. It associates a type name to a type so that it can be created and destructed dynamically at run-time. event – PySide6. When data values are exchanged between QML and C++, they are converted by the QML engine to have the correct data types as appropriate for use in QML or C++. If such a connection is made, and a signal triggered, the runtime warning will be shown: QObject::connect: Cannot queue arguments of type 'T' (Make sure 'T' is registered using qRegisterMetaType (). Note following line #include. This way your metatype will be registered once at startup, and the registration is close by the implementation and does not require to modify <code>main</code>. For pointer types, it also requires that the pointed to type is fully defined. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. ui. Note that some registers are read-only registers. Here's the twist: this class is contained in a shared library, and therefore I want to avoid instructing anyone using my library to call qRegisterMetaType. qRegisterMetaTypeしているにもかかわらずQObject::connectでランタイムエラーが出る場合の回避策. It's a bit tricky thing. Q_DECLARE_METATYPE (QSqlRecord) has to be outside any classes and namespaces. Hilk. Any class or struct that has a public default. new children are appended at. – pmf Feb 7, 2019 at 16:35 QObject::connect: Cannot queue arguments of type 'QTextCursor' (Make sure 'QTextCursor' is registered using qRegisterMetaType(). Nejat Nejat. If you use QMetaObject::invoke you've got an option to choose connection type - Direct or Queued. These are syntactically atrocious, but that’s templates for you. . A QVariant containing a pointer to a type derived from QObject will also return true for this function if a qobject_cast to the template type T would succeed. by using qRegisterMetaType(). Check if from PyQt5. It is more or less explained in the manual for int qRegisterMetaType (const char *typeName) This function requires that T is a fully defined type at the point where the function is called. In practice, both the Q_DECLARE_METATYPE() macro and the qRegisterMetaType() template function can be used to register custom types, but qRegisterMetaType() is only required if you need to perform signal-slot communication or need to create and destroy objects of the custom type at run-time. Also I get warnings: QObject::connect: Cannot queue arguments of type 'QTextBlock' (Make sure 'QTextBlock' is registered using qRegisterMetaType (). Call qRegisterMetaType () to make types available to non-template based functions, such as the queued signal and slot connections. Your code should look like this: Q_ENUM (StateEnum) //note the missing 'S' here Q_PROPERTY (StateEnum state READ state NOTIFY stateChanged) Share. ) I believe this is because I am updating the text box from threads other than the ma. That is, only Predefined C++ Types and custom objects that have Q_PROPERTY declarations could access from QML environment. Fixed a Qt warning about "cannot queue arguments of type. " and: "Warning: This function is useful only for registering an alias (typedef) for every other use case Q_DECLARE_METATYPE and qMetaTypeId() should be used instead. 3. . Save yourself the hassle and use QStringList. tag(); // prints MY_CUSTOM_TAG. e. qRegisterMetaType usage. Registering a metatype shouldn't prevent you from disconnecting a signal. This function requires that T is a fully defined type at the point where the function is called. The Connection class holds either a QTcpSocket or QTcpServer (depends on the config). Problem: There is no update of the UI. stackexchange. call qRegisterMetaType() to register the data type before you establish the connection. Thanks for the code snippet. 1 Answer. Now it works fine when pressButtonInsert is triggered but returns this. It works only in this case int qmlTypeId = qRegisterMetaType<namespace::MenuModel*> ("MenuModel*"); You return a pointer in the property, so Qt Meta Object system needs to know about it. uint8_t is the typedef for unsigned char . Detailed Description. I. One of the overloads is a function template that can be used to create an alias for a type and the form is: qRegisterMetaType<Type> ("alias"); That is, it wants to know the type for which you are declaring something. So using qRegisterMetaType () you will just trade Q_ENUM () for Q_DECLARE_METATYPE (). h" enum Color { RED = 0, BLUE, GREEN }; Q_DECLARE_METATYPE (Color) #endif /* ENUMS_H */. Even though we do not intend to use the type with QVariant in this example, it is good practice to also declare the new type with Q_DECLARE_METATYPE (). The related type must provide a public default constructor, a public copy constructor and a public destructor to be eligible to be declared as a metatype. launch, the quads in rviz cannot detect the enviroment and it shows QObject::connect: Cannot queue arguments of type 'QVector' (Make sure 'QVector' is registered using qRegisterMetaType(). As said in int qRegisterMetaType () documentation: To use the type T in QVariant, using Q_DECLARE_METATYPE () is sufficient. Convert this variant to type QMetaType::UnknownType and free up any. 2 Answers Sorted by: 3 You do not need to call qRegisterMetaType () to use a type with QVariant. The default value is Data8, i. Re: Q_DECLARE_METATYPE vs qRegisterMetaType for non global namespace classes (QTest) The reason for this behavior might be caused by the fact that runtime signal/slot connections are checked by string manipulation - both Q_DECLARE_METATYPE, SIGNAL, SLOT macros and 'moc' are (among other things). A common way to register the type is in main or with a static function register. 3. ) QObject::connect: Cannot queue arguments of type 'QModelIndex' (Make sure 'QModelIndex' is registed using qRegisterMetaType(). ) I read on some forum, that this may be caused by calling qt-functions from another Thread, and that using signals & slots instead of plain function calling may fix the issue, but i have tried signals aswell, and i. #define. 14. Got a similar example working without explicitly calling qRegisterMetaType() just by removing the semicolon from the line Q_DECLARE_METATYPE(StateMachine::state) QObject::connect: Cannot queue arguments of type 'QModbusDevice::State' (Make sure 'QModbusDevice::State' is registered using qRegisterMetaType (). (Make sure 'QDomDocument' is registered using qRegisterMetaType(). Any class or struct that has a public default. qRegisterMetaType<QSqlDatabase>("QSqlDatabase"); Just changing the signal to this form: void dbConnected(QSqlDatabase *db); And, in the slot side I'll use something like this: void onDBConnected(QSqlDatabase * const db); I'm concerned with the usage of db (as in the beginning I've made the reference const), so I make it const here. (Make sure 'QTextCharFormat' is registered using qRegisterMetaType(). h which looks like: #ifndef ENUMS_H #define ENUMS_H #include <QtDBus> #include "enumDBus. I realize that this actually works when more than one signal of different types is sent, e. Detailed Description. ) QObject: Cannot create children for a parent that is in a different thread. This requires the exchanged data to be of a type that is recognizable by the engine. The syntax gets especially interesting when specializing a template function of a. . This event handler can be reimplemented in a subclass to receive child events. With Q_DECLARE_METATYPE and without qRegisterMetaType: No warning, slot is called With Q_DECLARE_METATYPE and with qRegisterMetaType: No warning, slot is called. This class is registered as an uncreatable type so it can be referred by name in QML. Any class or struct that has a public default constructor, a public copy constructor, and a public destructor can be registered. connect (thread, SIGNAL (ShowData (QList<QString>)), this, SLOT (ev. In practice, both the Q_DECLARE_METATYPE() macro and the qRegisterMetaType() template function can be used to register custom types, but qRegisterMetaType() is only required if you need to perform. Each emission of the signal will append one item to the list, containing the arguments of the signal. Sets the port on the local side of a connection to port. All documented Qt functions listed alphabetically with a link to where each one is declared. 31. @pyqtSlot, in turn, is a decorator which converts simple python method to Qt slot. QAbstractSocket is the base class for QTcpSocket and QUdpSocket and contains all common functionality of these two classes. setContextProperty : Use setContextProperty, When you want to use a single global class to access to or from QML. QObject::connect: Cannot queue arguments of type 'QVector<int>'. It also reflects the size of the paging file at that time. All the resources I found online point to a C++ syntax/documentation. By convention, these files are given a . • Posting events with QApplication::postEvent(), or using queued signal/slot connections, are both safe mechanisms for communicating across threads but require the receiving thread. Its probably something about Qt, but how can i fix it ?Member Function Documentation [explicit] QQmlEngine:: QQmlEngine (QObject *parent = nullptr) Create a new QQmlEngine with the given parent. Execute qRegisterMetaType<QItemSelection> (); before it is used as such, e. 2. multithreaded software and I am getting the warning says: (Make sure 'QVector<int>' is registered using qRegisterMetaType (). Foo and Foo* are different types and need to be registered separately. Custom types registered using qRegisterMetaType() that have operators for streaming to and from a QDataStream can be stored using QSettings. cpp file. Readers will master both the C++ language and Qt libraries,. clicked. karensantana. #include<QMetaType> typedef QList<int> IntList; qRegisterMetaType<IntList> ("IntList"); error C2909: 'qRegisterMetaType': explicit instantiation of function template requires return type. Be very careful as cv::Mat is not implicitly shared, it is just shared (i. Also note that I have my sig/slots with a reference, but if I used a connect like this: @. If you use queued connections, you'll need to call qRegisterMetaType() too. 如果要使自定义类型或其他非QMetaType内置类型在QVaiant中使用，必须使用该宏Q_DECLARE_METATYPE。该类型必须有公有的 构造、析构、复制构造 函数 qRegisterMetaType 必须使用该函数的两种情况：1、如果非QMetaType内置类型要在 Qt 的属性系统中使用2、如果非QMetaType内置类型要在 queued 信号与槽 中使用。错误原因：. childKeys();@J. I also have to implement for cv::Mat type data. Following this logic, the following code may not work: connect (senderObject. Please visit robotics. self. Here You need create this class object before use setContextProperty (). org is deprecated as of August the 11th, 2023. MEMORYSTATUSEX reflects the state of memory at the time of the call. What is(are) the good place(s) to put the qRegisterMetaType call? I obviously don't want any expllicit initialization call from application code. Obviously then you would not do registerComparator (). ) QObject: Cannot create children for a parent that is in a different thread. a copy of a cv::Mat object will point to the same data as the copied from item). QObject: Cannot create children for a parent that is in a different thread. Section and Key Syntax# Setting keys can contain any Unicode characters. QtCore import QObject works. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. Unless the property is readonly, you can also set a binding on this property. QObject::connect: Cannot queue arguments of type 'object' (Make sure 'object' is registered using qRegisterMetaType(). It will return the same result if it was called before. Where are you getting this from? qRegisterMetaType is not a member function of QSettings or any other class. It is. Hi, you can try using a more robust flavor of connect() by adding an argument after the lambda, like this:We will still need to register it with the meta-object system at run-time by calling the qRegisterMetaType() template function before we make any signal-slot connections that use this type. Constantin. Here how connect looks in main constructor: connect (w1, SIGNAL (sentInt (int)), this, SLOT (receiveInt (int))); Such simple app works, but if i change parameters from int to "signed long long" it will give message during runtime and signal won't be emitted: QObject::connect: Cannot queue arguments of type 'signed long long'. My Thread is as. The stretch factor changes the width of all characters in the font by factor percent. It is. 如果要使用单个全局类来访问QML或从QML访问. The following code allocates and destructs an instance of MyClass:The Q_DECLARE_METATYPE() macro and qRegisterMetaType() function documentation contain more detailed information about their uses and limitations. From the docs: int qRegisterMetaType ( const char * typeName ) Registers the type name typeName to the type T. I explicitly don't want to update it on every change to one of the quantities, so they don't. Since you're passing the parameter via a pointer you don't need to register the type AFAIK. There is a name index for fast lookup of the meta type id. More frustrating is I've found PySide documentation alluding to the use of qRegisterMetaType, but I can't find out where to call it from. C++ (Cpp) qmlRegisterUncreatableMetaObject - 2 examples found. How to properly use qRegisterMetaType on a class derived from QObject? I couldn't understand from the answer to where I have to define the specialization of qMetaTypeConstructHelper. akshatrai91 7 Jan 2021, 06:21. (Make sure 'QTextCursor' is registered using qRegisterMetaType(). You should use qmlRegisterType function for that. e. import executer class Window(QtWidegets. beginGroup("references/"); QStringList keys = settings. In short, I get following error: QObject::connect: Cannot queue arguments of type 'cv::Mat' (Make sure 'cv::Mat' is registered using qRegisterMetaType (). Provide details and share your research! But avoid. ) I have defined MyStruct in an accessible header file: myheader. You could wrap the used functions and classes into custom widgets or plain py-files and in your main frame class only import those custom widgets. If it is a partial specialization it might be template<class X> instead. Make sure 'QTextCursor' is registered using qRegisterMetaType(). Your uint8_t is atomic and you don't need to register it, just use. Since Qt 5. 9k 13 13 gold badges 106 106 silver badges 138 138 bronze badges. QWidget): def __init__(self):. You can connect a signal to a slot with connect (). . Setting keys can contain any Unicode characters. In C++ if you wan't to use some type in queued connection type you should call qRegisterMetaType<MyType> ("MyType"). Then, connect this signal to a slot that will do the actual update of the data. Usually, we call the macro right below the class/struct declaration in the header file. Even though qRegisterMetaType(). Q&A for work. The following code allocates and destructs an instance of MyClass: Type names can be registered with QMetaType by using either qRegisterMetaType() or registerType(). To call qRegisterMetaType (), you still need to use Q_DECLARE_METATYPE (). First of all you need to declare your custom object for Qt metatype system. Note: This function is thread-safe. It provides functions for creating and manipulating selections, and selecting a range of items from a model. registerType () determines which register is used for the operations. Hello, when I run rviz_sim. Text cursors are objects that are used to access and modify the contents and underlying structure of text documents via a programming interface that mimics the behavior of a cursor in a text editor. ) but I do not think that relates with the phenomena. See QMetaType docs for more information. To make the type known to this class, we invoke the Q_DECLARE_METATYPE () macro on the class in the header file where it is defined: Q_DECLARE_METATYPE(Message); This now makes it possible for Message values to be stored in QVariant objects and retrieved later. When I try to build our existing. Call qRegisterMetaType() to make type available to non-template based functions, such as the queued signal and slot connections. Using the macro directly turned out to be impossible. MainWindow win; win. QObject::connect: Cannot queue arguments of type 'QVector<int>' (Make sure 'QVector<int>' is registered using qRegisterMetaType(). h. The point is, if we provided answer for any very unlikely situation, especially if caused by user mistake or file corruption we could know anything about, StackOverflow would become a galaxy of unnecessary questions (infinitely more than it is right now) with a billion of unlikely answers. qRegisterMetaType<B_Custom::B_Enum>() before call A::DoSomething(), the type value of function SomethingElse will not be QMetaType::UnknownType. Note that this only works for QObject subclasses which use the Q_OBJECT macro. Here’s the list of what changed: QVariant used to forward isNull () calls to its contained type – but only for a limited set of Qt’s own types. ). QMetaType:: Q_DECLARE_OPAQUE_POINTER (PointerType) This macro enables pointers to forward-declared types (PointerType) to be registered with QMetaType using either Q_DECLARE_METATYPE() or qRegisterMetaType(). 2、在类型定义完成后，加入声明：Q_DECLARE_METATYPE (MyDataType); 3、在main ()函数中. Follow answered Sep 16, 2014 at 4:21. qRegisterMetaType() since the names are resolved at runtime. ) What I'm trying to do is send a signal containing two cv::Mat images from a QThread to the main thread, so that I can display the output. If you want to pass IBase * between different threads, you need to register class with qRegisterMetaType<IBase *> () call; It is bad practice to pass pointers throught singals, because it is hard to control lifetime of passed objects. complains that the metatype isn't registered. Obviously then you would not do registerComparator (). tab) self. A more complex program sending QSharePointer objects using slots has a similar situation with GDB, that can be reproduced with the previous example. Improve this answer. Any QQmlContext's created on this engine will be invalidated, but not destroyed (unless they are parented to the. Learn more about TeamsAh I found the problem, which was a logic problem. You'll need Q_DECLARE_METATYPE () if you want to store your type within a QVariant and you will additionally need qRegisterMetaType<> () if you want to dynamically create and destroy objects of that type at runtime, mostly for queued signal and slots connections or the QObject property system. 1、自定MyDataType 类型，在这个类型的顶部包含：#include <QMetaType>. If you need a socket, you have two options: Instantiate QTcpSocket or QUdpSocket. com to ask a new question. qRegisterMetaType 将某类型注册中 MetaType 系统中. ) But if I change the Q_DECLARE_METATYPE call to: namespace my_namespace { Q_DECLARE_METATYPE(BathyHint) } everything workes fine. qml:17: Error: Unknown method parameter type: const Person*. If I save the image to disk in the DB thread just after emitting the signal, it is good. 9k 9 34 52. As you have already found out, you must use Q_DECLARE_METATYPE to make the type known to Qt. The. In variant 1 the call is invoked immediately like in direct connection. 我们知道类中的成员函数并不一定会被调用(即，该宏并不确保类型被注册到MetaType)。 通过qRegisterMetaType可以确保类型被注册; 两个qRegisterMetaType 的联系如果还希望使用这种类型的引用，可同样要注册：qRegisterMetaType<TextAndNumber>("TextAndNumber&"); 版权声明：本文为wangzhiqian7hao原创文章，遵循 CC 4. QBluetoothDeviceInfo which provides similar information for remote devices. Data Type Conversion Between QML and C++. Q_ASSERT_X (normalizedTypeName == QMetaObject::normalizedType (normalizedTypeName. 0, so Q_ENUM is my variant. struct StandardData { int EmpId; QString Name; }; Q_DECLARE_METATYPE (StandardData) Additionally, you might need to call qRegisterMetaType. 2] enum QLocalSocket:: SocketOption flags QLocalSocket:: SocketOptions This enum describes the possible options that can be used to connect to a server. Can you show the code that's actually causing the. ) So it seems to be a multi-threading issue caused by this instruction connect (process,&QProcess::started, [this. 2 Answers. This function was introduced in Qt 5. new children are appended at. cpp2 Answers. close file : AnaEx01. Undeclared QMetaObject::SuperData. # 打开 rviz时 QObject::connect: Cannot queue arguments of type 'QVector<int>' (Make sure 'QVector<int>' is registered using qRegisterMetaType(). ); RealTimeHistogram: the main widget, a user interface; DataGeneratorThread class DataGeneratorThread. #include<QMetaType> typedef QList<int> IntList; qRegisterMetaType<IntList> ("IntList"); error C2909: 'qRegisterMetaType': explicit. Qt::QueuedConnection，则会发送一个QEvent，并在应用程序进入主事件循环后立即调用该成员。. You are looking for the Q_ENUM () macro. rep file extension, short for Replica. Reply Quote 0. Note: If you want to use your custom metatypes also in queued slot connections or with QMetaMethod, you have to call qRegisterMetaType<QPushButton*>() Share. QtCore. The key bit here is that the handle. Just installing it did not work for me. runBtn. Even though we do not intend to use the type with QVariant in this example, it is good practice to also declare the new type with Q_DECLARE_METATYPE(). if the permission has been granted, it continues with the next permission in the list. receiver. I don't really know what I have to do in addition. Note: Since all expressions evaluated in QML are evaluated in a particular context, if the context is. Detailed Description. Thus the following will fail. This function was introduced in Qt 5. By implementing a factory it is possible to create custom QNetworkAccessManager with specialized caching, proxy and cookie support. Use evaluate () to evaluate script code; this is the C++ equivalent of the built-in script function eval (). (Make sure 'QVector<int>' is registered using qRegisterMetaType(). g. I tested your code on Qt 5. 11. Using qRegisterMetaType() is actually registering a certain type to QMetaType. ) @. Data Type Conversion Between QML and C++. template<class T> QMetaObject::Connection connect_from_pointer ( const QSharedPointer<T>& sender,. Note that if you intend to use the type in queued. QtのAPIのドキュメントに、thread-safeと書いてない限りは、QMutex等を使って自分で排他をする必要がある。. 9k 13 13 gold badges 106 106 silver badges 138 138 bronze badges. launch" i got. (Make sure 'QVector' is registered using qRegisterMetaType(). 9 under OSX 10. h file. Follow answered Jan 29, 2016 at 11:01. get (), &senderObject::signal, this, [this] (int int_val, std::string str_value) {function (int_val,str_value)}); Maybe there is an overload template. 3. (Parent is QTcpSocket (0x24a6ce8), parent's thread is ServiceSlots. multithreaded software and I am getting the warning says: (Make sure 'QVector<int>' is registered using qRegisterMetaType (). runtime barfs if the signature for test in both headers and . Debugging signals and slots connections. 0. If a field is empty, keep it in the result. I am trying to learn Qt and I am attempting to do so by making a little titres game. If you are using those metatypes during. 12. ) changing rowCount in the main thread or commenting out setRowCount call in change_row_count() makes those errors. I'm introducing myself to PyQt5 through one of its included examples. FollowThis can be made to work but it turns out there's a bit of manual labour to be done. Returns true if the write succeeded; otherwise returns false. QObject::connect: Cannot queue arguments of type 'QAbstractSocket::SocketState' (Make sure 'QAbstractSocket::SocketState' is registered using qRegisterMetaType(). ChildAdded and ChildRemoved events are sent to objects when children are added or removed. qRegisterMetaType <Card::Orientation> ( "Card::Orientation" ); QSignalSpy. There is no use case for implementing qRegisterMetaType, because PyObject. Any class or struct that has a public default constructor, a public copy constructor and a public destructor.