QMetaType is Qt's way to have run-time dynamic information about your types. 子线程中：QMap<QString, QString> testMap; emit testSignal(testMap);Call qRegisterMetaType() to make type available to non-template based functions, such as the queued signal and slot connections. I pass the MyClass pointer to the streaming operator and only stream things like QString, QPointF, etc. Even though qRegisterMetaType(). QAbstractSocket is the base class for QTcpSocket and QUdpSocket and contains all common functionality of these two classes. The members of the class contain calls to qRegisterMetaType We can also use Q_DECLARE_METATYPE to declare custom variables, and package custom. I read on documentation that Q_DECLARE_METATYPE makes available type to QVariant, for example (I got it from documentation): @ struct MyStruct { int i;. ) ^C[rviz-2] killing on exit [laserMapping-1] killing on exit Hello guys, i have the following message when i run the launch file. Did you try to use qRegisterMetaType function? The official manual says: The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. qRegisterMetaType you'll need if creating objects by class name dynamically, and it seems for queued connections, generally you won't. One of these plugins uses Q_DECLARE_METATYPE on some types that need to be stored in a QVariant. Sets the factory to use for creating QNetworkAccessManager (s). Here You need create this class object before use setContextProperty (). Your code should look like this: Q_ENUM (StateEnum) //note the missing 'S' here Q_PROPERTY (StateEnum state READ state NOTIFY stateChanged) Share. The file (called a "rep" file) uses a specific (text) syntax to describe the API. Data Type Conversion Between QML and C++. Use Q_DECLARE_OPAQUE_POINTER () to be able to register pointers to forward. on top of main. – Kamil Klimek. 0, so Q_ENUM is my variant. To call qRegisterMetaType (), you still need to use Q_DECLARE_METATYPE (). The Qt doc on qRegisterMetaType explicitly says : T must be declared with Q_DECLARE_METATYPE (). Setting keys can contain any Unicode characters. Use it if you want to use it as a global enumerator and then you need to call the meta-type runtime registration from the library, not from the application. But the problem comes up when I try to send it to C++ slot, that have my enum as parameter. You should use Q_DECLARE_METATYPE macro for this. For the moment, moc will extract and record all tags, but it will not handle any of them specially. 052592317]: Writing. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. qRegisterMetaType<QAbstractSocket::SocketState>(); Share. I explicitly don't want to update it on every change to one of the quantities, so they don't. connect(self. QAbstractSocket is the base class for QTcpSocket and QUdpSocket and contains all common functionality of these two classes. 2 Answers Sorted by: 3 You do not need to call qRegisterMetaType () to use a type with QVariant. ) QObject: Cannot create children for a parent that is in a different thread. Note that some registers are read-only registers. An "ugly solution" would be to hack the fairly simple QSignalSpy code in order to handle the reference passed arguments. ) So it seems to be a multi-threading issue caused by this instruction connect (process,&QProcess::started, [this. QtCore import * from PyQt5. #include <QObject> #include <QVariant> class Record : public QPair<qreal, qreal> {. It provides functions for creating and manipulating selections, and selecting a range of items from a model. In QML, the meta-type system is the only way that QML engine can access C++ structures from a QML environment. Returns a list of child objects. Asking for help, clarification, or responding to other answers. qRegisterMetaType<Subclass> ("Subclass") also doesn't work. QScriptEngine myEngine; QScriptValue three = myEngine. ) But if I change the Q_DECLARE_METATYPE call to: namespace my_namespace { Q_DECLARE_METATYPE(BathyHint) } everything workes fine. 2. (Make sure 'QVector<int>' is registered using qRegisterMetaType(). 1. (Make sure 'QTextCharFormat' is registered using qRegisterMetaType(). Any class or struct that has a public default constructor, a public copy constructor, and a public destructor can be registered. I created a. (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 (). 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。. Oct 17, 2014 at 14:12. You should use qmlRegisterType function for that. mycompany. QSignalSpy can connect to any signal of any object and records its emission. The key bit here is that the handle. said, try to directly pass shared_ptr with your signal/slots. QObject::connect: Cannot queue arguments of type 'my_enum' (Make sure 'my_enum' is registered using qRegisterMetaType(). 使用此连接类型在同一线程中的对象之间进行. template <typename T> struct QMetaTypeId<Container<T>>. Obviously then you would not do registerComparator (). Here my test code and example: #include <QCoreApplication> #include <QDebug> #include <QMetaType> #include <QRect> #include <QMetaObject> class. call qRegisterMetaType() to register the data type before you establish the connection. It associates a type name to a type so that it can be created and destructed dynamically at. That is, only Predefined C++ Types and custom objects that have Q_PROPERTY declarations could access from QML environment. ) From what I've read, this should totally work. There is a name index for fast lookup of the meta type id. Note that the signal has to be in normalized form, as returned by normalizedSignature (). Save yourself the hassle and use QStringList. Any class or struct that has a public default constructor, a public copy constructor, and a public destructor can be registered. #pragma once #include <QObject> class MyClass : public QObject { Q_OBJECT public: static void initQML (); MyClass (); MyClass (const MyClass &myClass. You only. Represents a handle to a signal-slot (or signal-functor) connection. This requires the exchanged data to be of a type that is recognizable by the engine. Call qRegisterMetaType<std::string> (); in the initialization of your code. qRegisterMetaType 将某类型注册中 MetaType 系统中. (Make sure 'QVector<int>' is. Also note that I have my sig/slots with a reference, but if I used a connect like this: @. The Qt doc on qRegisterMetaType explicitly says : T must be declared with Q_DECLARE_METATYPE (). My original script use this : from PyQt5. ) ^C[rviz-2] killing on exit [laserMapping-1] killing on exit Hello guys, i have the following message when i run the launch file. Any class or struct that has a public default. you don't call qRegisterMetaType multiple times, even with the same type and the same string. I'm writing python library for very simple text output to Qt's QTextBrowser window (stored in window. Variant 3: use MACRO instead of std::invoke in variant 2. self. 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. 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。. pro file: CONFIG += qmltypes. py that implements a customwidget class it would look something like: from customwidgetscript import customwidget. It seems QVariant is not direct part of queued connections mechanism. (Make sure 'QTextCursor' is registered using qRegisterMetaType (). QT 信号和槽传递自定义对象问题. 1 Answer. Problem using qRegisterMetaType. The qRegisterMetaType function essentially allows a typedef or alias to be assigned to a QVariant. I'm not sure how to do this in python but. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. tag(); // prints MY_CUSTOM_TAG. I understand that it has to do with Qt library but in which cpp file i have to put the argument ? The argument is this right ? qRegisterMetaType<QVector<int> >. MyEnum needs to be registered with qRegisterMetaType. When you think about, there are quite convincing reasons to disallow it implicitly happening. ) QObject::connect: Cannot queue arguments of type 'QVector' (Make sure 'QVector' is registered using qRegisterMetaType(). Notice that with this approach you will only be able to check the value of the passed. Any class or struct that has a public default constructor, a public copy constructor, and a public destructor can be registered. )@. Use wakeOne() to wake one randomly selected thread or wakeAll() to wake them all. There was a short discussion about this here. 14. 2 Answers. (Make sure 'QVector' is registered using qRegisterMetaType(). To use the type T in queued signal and slot connections, qRegisterMetaType<T>() must be called before the first connection is established. If it gets destroyed elsewhere (passing by ref doesn't bump the ref count), your callback/lambda may crash. Also, to use type T with the QObject::property () API,. call qRegisterMetaType with the name specified, else reading properties. FollowThis can be made to work but it turns out there's a bit of manual labour to be done. Hilk. 9 under OSX 10. emit (statuses) Share. It just allows you to queue types that. Then, connect this signal to a slot that will do the actual update of the data. QTextCursor contains information about both the cursor's position within a QTextDocument and any selection that it has made. qRe gisterMetaType 的函数原型为： ```c++ template < type name T> int. M. 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. 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++. QObject::connect: Cannot queue arguments of type 'QVector<int>' (Make sure 'QVector<int>' is registered using qRegisterMetaType(). When a new folder is selected I load the thumbnails and. ;. Also, to use type T with the QObject::property() API, qRegisterMetaType<T>() must be called before it is used, typically in the constructor of the class that uses T, or in the main() function. In C++ if you wan't to use some type in queued connection type you should call qRegisterMetaType<MyType> ("MyType"). karensantana. Fixed a Qt warning about "cannot queue arguments of type. I am also using some in queued signal and slot connections. . See also qRegisterMetaType(). See QMetaType docs for more information. Returns the access specification of this method (private, protected, or public). Variant 2: use std::invoke inside a lambda, which is passed to QMetaObject::invoke. しかし、Qtを使っている場合は、わざわざ自分でMutexの管理をしなくても、スレッドとのデータのやり取りを全て signal/slotでやってしまい、共有データを. ros. Using qRegisterMetaType() is actually registering a certain type to QMetaType. The following code: self. struct StandardData { int EmpId; QString Name; }; Q_DECLARE_METATYPE (StandardData) Additionally, you might need to call qRegisterMetaType. )Note: If the setting is set before opening the port, the actual serial port setting is done automatically in the QSerialPort::open () method right after that the opening of the port succeeds. FollowQObject::connect: Cannot queue arguments of type 'QProcess::ProcessError' (Make sure 'QProcess::ProcessError' is registered using qRegisterMetaType(). How to register custom type with QML if it is passed as const from C++. Note that this only works for QObject subclasses which use the Q_OBJECT macro. So I played around, copied the original macro and adapted it a bit: @. 11. " 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. QTextCharFormat. One of these objects is a Connection. See also disconnect(), sender(), qRegisterMetaType(), Q_DECLARE_METATYPE(), and Differences between String-Based and Functor-Based Connections. It provides functions for creating and manipulating selections, and selecting a range of items from a model. . What is(are) the good place(s) to put the qRegisterMetaType call? I obviously don't want any expllicit initialization call from application code. To avoid never ending notification loops you can temporarily block signals. Originally I was passing a pointer to a type to signals which worked, the slots obviously had to returned the same pointer, again this worked. Where are you getting this from? qRegisterMetaType is not a member function of QSettings or any other class. tab) self. 12. Haven't tried it yet but it appears to check the permissions established in the manifest(?). newStatuses. – folibis. 1 Answer. 4. For example if you have a customwidgetscript. ) The image I am trying to pass is a cv::Mat which I converted to a QImage which I afterwards converted to a QString. When a signal is emitted, the corresponding signal handler is invoked. I guess it's the qRegisterMetaType () call itself that's missing. 二者的联系： QMetaTypeId<TYPE>的类中的成员包含对qRegisterMetaType的调用. import executer class Window(QtWidegets. g. 2 @Alfredocubitos would it be possible to share an example of the threaded websocket. cpp; so you will have. QObject::connect: Cannot queue arguments of type 'QVector<int>'. ) QObject::connect: Cannot queue arguments of type 'QModelIndex' (Make sure 'QModelIndex' is registed using qRegisterMetaType(). and another folder with the obj files. 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. Note: If you want to use your custom metatypes also in queued slot connections or with QMetaMethod, you have to call qRegisterMetaType<QPushButton*>() Share. On this windows 7 machine, I have installed Python 3. ) My application is an image viewer. The connection in question is queued. Maybe qRegisterMetaType is what you missed. Learn more about TeamsAh I found the problem, which was a logic problem. QObject::connect: Cannot queue arguments of type 'uint32_t' (Make sure 'uint32_t' is registered using qRegisterMetaType(). (Make sure 'uint64' is registered using. ui). Any class or struct that has a public default constructor, a public copy constructor, and a public destructor can be registered. This article will describe what you. Connect and share knowledge within a single location that is structured and easy to search. It can be done with some global container, but because in C++ order of initializing variables is not defined - it may be not trivial. Note: Signals are always public, but you should regard that as an implementation detail. This has been changed, and isNull () now only returns true if the QVariant is empty or contains a nullptr. I created a. If you are using the Python logging module to can easily create a custom logging handler that passes the log messages through to a QPlainTextEdit instance (as described by Christopher). Share. e. iv. I'm not sure how to do this in python but probably you should add similar call with QTextCursor. 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QObject::connect: Cannot queue arguments of type 'QHostAddress' (Make sure 'QHostAddress' is registered using qRegisterMetaType(). 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. The compound types are then created by association of one or more of the primitive types in arrays, dictionaries or structures. 1. This class can tell the outside world that its state has changed by emitting a signal, valueChanged(), and it has a slot which other objects can send signals to. the type name must be specified without the class, as in. 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. One or many threads can block waiting for a QWaitCondition to set a condition with wakeOne() or wakeAll(). Check if from PyQt5. stackexchange. ). This maybe is not the nicest solution, but it works just fine: Add a property to the wizardpage which contains the QListView and let it return the pointer to the selectionmodel. clicked. 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. 1,609 4 22 34. # 打开 rviz时 QObject::connect: Cannot queue arguments of type 'QVector<int>' (Make sure 'QVector<int>' is registered using qRegisterMetaType(). 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 a field is empty, keep it in the result. qRegisterMetaType<B_Custom::B_Enum>() before call A::DoSomething(), the type value of function SomethingElse will not be QMetaType::UnknownType. Sorted by: 5. qRegisterMetaType 将某类型注册中 MetaType 系统中. 12. It seems that for a metatype that is a QList<MyClass::MyEnum> I must. v. In conclusion: Don't use Q_DECLARE_METATYPE and qRegisterMetaType for your QObject enum. (Make sure. So using qRegisterMetaType () you will just trade Q_ENUM () for Q_DECLARE_METATYPE (). The Qt GUI module contains classes for 2D graphics, imaging, fonts, and advanced typography. open(wsUrl); without threading the connection works fine. When the plugin is reloaded later, the old declaration still points to the original memory space of the now-unloaded library. The SplitBehavior type is a typedef for QFlags <SplitBehaviorFlags>. In my module tests, I turn the card up and down, and can verify that the number of signals are increasing using QSignalSpy. The factory must be set before executing the engine. 就是说 类实列化一次，QML中可以直接使用这个类。. QObject::connect: Cannot queue arguments of type 'QList<QPersistentModelIndex>' (Make sure 'QList<QPersistentModelIndex>' is registered using qRegisterMetaType(). Any class or struct that has a public default constructor, a public copy constructor, and a public destructor can be registered. SIGNAL(ueSignalTaskFinished(UePosCommProtocolArch::UeCommand&, // reference QByteArray&)), //dittoCustom types registered using qRegisterMetaType() that have operators for streaming to and from a QDataStream can be stored using QSettings. ;. This site will remain online in read-only mode during the transition and into the foreseeable future. " Currently I have no UI implemented (yet!). In variant 1 the call is invoked immediately like in direct connection. 0. It can be used to check if the connection is valid and to disconnect it using disconnect(). 0. Q_DECLARE_METATYPE (QSqlRecord) has to be outside any classes and namespaces. 根据类型名. Tour Start here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this siteThis macro is used to specialise the template class QMetaTypeId with typename TYPE, in which, a static member function qt_metatype_id () is defined. multithreaded software and I am getting the warning says: (Make sure 'QVector<int>' is registered using qRegisterMetaType (). You can connect a signal to a slot with connect () and destroy the connection with disconnect () . Note: This function is thread-safe. complains that the metatype isn't registered. Consider for example the following (hypothetical) code:The Listmodel should be modified by an AMQP-Eventqueue. The following code allocates and destructs an instance of MyClass:使用Q_DECLARE_METATYPE()可以让这个数据类型T放到QVariant里面。如果想以队列的方式让T使用信号与槽，当第一次连接的时候就要调用qRegisterMetaType<T>()。 QObject::property()要和类型T一起使用，这个时候qRegisterMetaType<T>()要提前调用。This enum specifies how the split () functions should behave with respect to empty strings. Now the above code compiles and runs just fine. . Just installing it did not work for me. The Windows registry and INI files use case-insensitive keys, whereas the CFPreferences API on macOS and iOS uses case. . Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. Any class or struct that has a public default constructor, a public copy constructor and a public destructor. 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In part II of our Qt for Beginners Summer Webinar Series we will explore how Qt is so much more than just a GUI toolkit. Otherwise, returns QPartialOrdering::Less, QPartialOrdering::Equivalent or QPartialOrdering::Greater if lhs is less than, equivalent to or. To enable creation of objects at run-time, call the qRegisterMetaType () template function to register it with the meta-object system. Even if it works now, it may fail with new Qt versions. If you need a socket, you have two options: Instantiate QTcpSocket or QUdpSocket. Usually, I do this type of updates using signals and slots, but the run function is not PyQt specific. qRegisterMetaType<foo::FooState>(); Question. Replacing it with "%matplotlib qt5" (or deleting it entirely) worked for me. Here is the list of information kept for each type in the meta-type system: The Type Name as registered. Last updated at 2016-07-08 Posted at 2015-11-16. qRegisterMetaType <rQJsonObject> ("rQJsonObject"); With this: no matching function for call to 'qRegisterMetaType'. qRe terMetaType 是Qt框架中的一个函数，用于在Qt元对象系统中注册自定义的数据类型。. @RIJIK "very unlikely" doesn't mean never ever. If you are using queued connections, you need to register std::string as meta type. If I save the image to disk in the DB thread just after emitting the signal, it is good. Edit: from @altaf comments : To clarify, the root of the problem was cause by qRegisterMetaType<Data> ("Data"); in my main. like this: class ListPage : public QWizardPage { Q_OBJECT Q_PROPERTY (QItemSelectionModel* selectionModel READ selectionModel) public:. 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. Detailed Description. You could try using registerConverter () to allow implicit conversion of the shared_ptr<int> to a regular int, and compare them that way. Now you have a valid QObject. As you have already found out, you must use Q_DECLARE_METATYPE to make the type known to Qt. cppuint64 is a typedef for 64 bit integers in VS: Qt Code: Switch view. 0 BY-SA 版权协议，转载请附上原文出处链接和本声. Detailed Description. A connection defines an interface for sending/receiving data independent of the protocol. Returns the internal ID used by QMetaType. When the Citizen object is moved to the new thread the QNetworkAccessmanager still has its thread affinity set to. That's created by this macro. complains that the metatype isn't registered. The. otherwise. Consider the specific case of qRegisterMetaType. In that case, I think you need to register them. Improve this answer. All the resources I found online point to a C++ syntax/documentation. – pmf Feb 7, 2019 at 16:35QObject::connect: Cannot queue arguments of type 'QTextCursor' (Make sure 'QTextCursor' is registered using qRegisterMetaType(). You can create Q_GADGETS in QML using a C++ factory object registered to be accessible in QML, and a Q_INVOKABLE function in this factory which returns an instance of the Q_GADGET object. C++ (Cpp) qmlRegisterUncreatableMetaObject - 2 examples found. g. 2. Improve this answer. In short, I get following error: QObject::connect: Cannot queue arguments of type 'cv::Mat' (Make sure 'cv::Mat' is registered using qRegisterMetaType (). QWidget): def __init__(self):. ) I got the hint "expected a declaration" when I tried to use qRegisterMetaType from the global scope in my cpp file. QNativeSocketEngine::write () was not called in QAbstractSocket::ConnectedState. Consider the specific case of qRegisterMetaType. on_click) binds signal of a button (clicked) to a slot self. However, I cannot figure out how to verify that the included parameter is FACE_UP or FACE_DOWN. However documentation of qRegisterMetaType() says: "Call this function to. The following example illustrates how a structure containing an integer and a string. In general, you only need Q_DECLARE_METATYPE (). You only need to call qRegisterMetaType () if the type will be used in queued signal/slots connections, or with the QObject::property API. So if you put the register in constructor, you have to instance your class once and then make the connection. ) Bug is reproducable only if a queued connection is used (when objects are in different threads or explicit Qt::QueuedConnection is used) and MyType is declared inside a namespace. QObject::connect: Cannot queue arguments of type 'MyStruct'. A QItemSelection is basically a list of selection ranges, see QItemSelectionRange. QSignalSpy itself is a list of QVariant lists. In short, I get following error: QObject::connect: Cannot queue arguments of type 'cv::Mat' (Make sure 'cv::Mat' is registered using qRegisterMetaType (). (Make sure 'QTextBlock' is registered using qRegisterMetaType (). 048771190]: Out drawPath [ INFO] [1432901455. This event handler can be reimplemented in a subclass to receive child events. This implies that you can create bindings that use this property as a dependency or install QPropertyObserver objects on this property. root - done ----> Histograms and ntuples are saved 1 event has been kept for refreshing and/or reviewing. 9k 13 13 gold badges 106 106 silver badges 138 138 bronze badges. The QML engine provides built-in support for a. 2. I my real world application Context holds a large number of physical quantities (masses, forces, velocities,. The QML engine provides built-in support for a large number. Share. hEvaluating Scripts. 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 (). if the permission was not granted or has been changed to NOT granted, the user is asked to grant permission. com to ask a new question. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. If you want both, then register both. 2. qmlRegisterType makes the QObject (MyClass) class accessible in QML (Q_PROPERTY, Q_ENUM, Q_SIGNAL, Q_SLOT, Q_INVOKABLE, etc. 5] int qRegisterMetaType (QMetaType meta) Registers the meta type meta and returns its type Id. qml:17: Error: Unknown method parameter type: const Person*. Hello! connect( threadEstudo, SIGNAL( sinalResultados ( QList<analysis_results>)), this, SLOT( slotAvaliaResultadosEstudo ( QList<analysis_results>))); You may notice that I put the qDebug () so I can check if all metatypes were correctly registered, and the result was. 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 (). Currently I have a 2d array which represents the game board. QObject::connect: Cannot queue arguments of type 'CComPtr<IDeckLinkVideoFrame>' (Make sure 'CComPtr<IDeckLinkVideoFrame>' is registered using qRegisterMetaType(). So I saw this in the documentation: typedef QString CustomString;. FlightTab:Changed effect to 0 You do not have the required permissions to view the files attached to this post. ) QObject::connect: Cannot queue arguments of type 'QTextCursor'. 138: 139: This example shows a typical use case of Q_DECLARE_METATYPE(): 140: 141 snippet code/src_corelib_kernel_qmetatype. The QML engine provides built-in support for a. To enable creation of objects at run-time, call the qRegisterMetaType () template function to register it with the meta-object system. This property holds the state (high or low) of the line signal DTR. But the thing is, I have. QObject::connect: Cannot queue arguments of type 'QAbstractSocket::SocketState' (Make sure 'QAbstractSocket::SocketState' is registered using qRegisterMetaType(). 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. For example, this registers a Python class ‘MySliderItem’ as a QML type named ‘Slider’ for version ‘1. This requires the exchanged data to be of a type that is recognizable by the engine. I searched the Doc but I could not find a documentation to. Finds signal and returns its index; otherwise returns -1. QBluetoothDeviceInfo which provides similar information for remote devices. An alternative would be to wrap shared_ptr<int> in your own class and implement comparison the way you want.