Here my test code and example:但是如何传递一个程序员自定义的结构体？ 1）在定义结构体之后，要调用Q_DECLARE_METATYPE，向QT声明这个结构体 2）在main. To start viewing messages, select the forum that you want to visit from the selection below. One of these plugins uses Q_DECLARE_METATYPE on some types that need to be stored in a QVariant. I just found multiple examples showing the usage of Q_ENUM and Q_ENUMS and looking into the definition of Q_ENUM showed me that it includes Q_ENUMS and other definitions. If you only want to store pointer to Foo with the metatype system, then use qRegisterMetaType<Foo *> ();. All Qt Overviews. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries. int videoSourceMetaTypeId = qRegisterMetaType< VideoSource > ();Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. This macro is used to specialise the template class QMetaTypeId with typename TYPE, in which, a static member function qt_metatype_id () is defined. But I couldn't register the type because it's a QObject and I don't have access to the implementation to change it. When the plugin is reloaded later, the old declaration still points to the original memory space of the now-unloaded library. 1. 4 and it seems to work. Qt. e. This may make certain type comparisons fail. But at run time, I got below error:1 Answer. Also, to use type T with the QObject::property () API, qRegisterMetaType () must be. 14 vs 5. Call qRegisterMetaType() to register the data type before you establish the connection. An alternative would be to wrap shared_ptr<int> in your own class and implement comparison the way you want. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. Note that if you intend to use the type in queued signal and slot connections or in QObject 's property system, you also have to call qRegisterMetaType () since the names are resolved at runtime. Quote: bool QVariant::operator==(const QVariant & v) const. Q_DECLARE_METATYPE vs qRegisterMetaType for non global namespace classes. 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. Trying to register std::map<non_template_type_1,non_template_type_2> with Q_DECLARE_METATYPE() results in compilation failure and apparently is not supported. x however, the code generated by moc will call qRegisterMetaType for you if moc can determine that the type may be registered as a. Don't use Q_DECLARE_METATYPE and qRegisterMetaType for your QObject enum. Note that if you intend to use the type in queued signal and slot connections or in QObject 's property system, you also have to call qRegisterMetaType () since the names are resolved at runtime. the type name must be specified without the class, as in. 3. Detailed Description The QMetaType class manages named types in the meta-object system. Call qRegisterMetaType() to make type available to non-template based functions, such as the queued signal and slot connections. Sorted by: 5. ) I have defined MyStruct in an accessible header file: myheader. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. It associates a type name to a type so that it can be created and destructed dynamically at run-time. I want to use drag-and-drop to drag a QTreeWidgetItem that has std::shared_ptr user data. 8. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. 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(). This object can then be passed from QML to C++ via Q_INVOKABLE. To use the type T in queued signal and slot connections, qRegisterMetaType () must be called before the first connection is established. Question: Is there a way to check at compile-time if qRegisterMetaType<T> () was called for a custom type T? The custom type T needs to be registered in Qt meta-type system in order to be used in e. QList of Custom Objects. Accessing an enum stored in a QVariant. This allows me to use this type in a Q_PROPERTY, this all. Franzk 26 May 2011, 06:59. As said in int qRegisterMetaType () documentation: To use the type T in QVariant, using Q_DECLARE_METATYPE () is sufficient. You may have to register before you can post: click the register link above to proceed. 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. 1. complains that the metatype isn't registered. Is your feature request related to a problem? No, it's an improvement Please describe. Any errors from Qt's metatype systems are usually due to MOC (the "meta-object compiler"), which reads your header files and generates a "moc" file with metatype information for every class where the Q_OBJECT macro is declared. 4. Then you should register your object to use it with QML. QObject::connect: Cannot queue arguments of type 'MyStruct'. Q_DECLARE_METATYPE is required to store type with QVariant, those two are required to register object's "big three" to manage it as resource and its serialization methods. I am also using some in queued signal and slot connections. This is by design. Registers the type name . One of these plugins uses Q_DECLARE_METATYPE on some types that need to be stored in a QVariant. It associates a type name to a type so that it can be created and destructed dynamically at run-time. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. } But you'll most likely need to abstract the Q_DECL_EXPORT part so it is a Q_DECL_IMPORT in right circumstances, as described in Creating Shared Libraries. Q_DECLARE_METATYPE(NSP::MyStruct) qRegisterMetaTypeIt associates a type name to a type so that it can be created and destructed dynamically at run-time. staticMetaObject is of type QMetaObject and provides access to the enums declared with Q_ENUMS. Any idea what I'm missing please? BTW, no problem at all using Schedule in QMetaProperty or QVariant. Execute qRegisterMetaType<QItemSelection> (); before it is used as such, e. Read and abide by the Qt Code of Conduct. M. qRegisterMetaType vs. Type is not registered, please use the Q_DECLARE_METATYPE macro to make it known to Qt's meta-object system. Some structure need to be registered to be queued in asynchronous signals using qRegisterMetaType<T>(name), such as signal which passes QVector<int>. [since 6. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. [quote author="Andre" date="1306394817"]In that case, I think you need to register them. The Q_DECLARE_METATYPE() macro and qRegisterMetaType() function documentation contain more detailed information about their uses and limitations. To use the type T in queued signal and slot connections, qRegisterMetaType<T>() must be called before the first connection is established. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. –To copy to clipboard, switch view to plain text mode. cruz Hello, To be completely candid, I haven't used GDB remotely and I'm certainly not so intimate with it for the log to speak to me much. As the docs state: Declare new types with Q_DECLARE_METATYPE () to make them available to QVariant and other template-based functions. When using signals and slots with multiple threads, see Signals and Slots Across Threads. It is only useful to the code that follows it, in the same file. The class is used to send arguments over D-Bus to remote applications and to receive them back. Last updated at 2016-07-08 Posted at 2015-11-16. Step 1 (mark for MOC), build some QObjects That pattern uses Q_PROPERTY and Q_OBJECT and the MoC tool. [virtual] QLocalSocket:: ~QLocalSocket Destroys the socket, closing the connection if necessary. So, you don't want 'Widget' to be a metatype, you want 'Widget*' to be a metatype so that you can put a Widget* in a QVariant for example. qRegisterMetaType vs. 6. Sorted by: 1. QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_REGISTER_METATYPE() and qRegisterMetaType(). Also Q_DECLARE_METATYPE does not register a type, but declares it. Equivalent to Q_DECLARE_METATYPE(TYPE *) and Q_DECLARE_METATYPE(QQmlListProperty<TYPE>) QML_DECLARE_TYPEINFO (Type, Flags) Declares additional properties of the given Type as described by the specified Flags. QList<T> isn't really a pre-defined variant type (except QList<QVariant>) so it technically resolves to a QMetaType::UserType. The Q_DECLARE_METATYPE () macro also makes it possible for these values to be used as arguments to signals, but only in direct signal-slot connections. The third without Q_DECLARE_METATYPE. You can use Q_DECLARE_METATYPE(Widget*) but it is not needed as of Qt. View Profile View Forum Posts View Articles Beginner Join Date Nov 2014 Posts 6 Qt products. 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(). h. Then you should register your object to use it with QML. What you made is a const pointer to a non-const T; but top-level consts in function signatures are not part of the function. 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: This now makes it possible for Message values to be stored in QVariant objects and retrieved later. This now makes it possible for Message values to be stored in QVariant objects and retrieved later. canConvert<x> (); } and. Qt5でシグナルの引数としてユーザー定義型を指定する場合は、 Q_DECLARE_METATYPE と qRegisterMetaType () を使って方の登録を行う必要が. // to be declared somewhere Q_DECLARE_METATYPE(std::string); // to be invoked at the beginning of program qRegisterMetaType<std::string>(); Without type registration Qt doesn't know how to do. In the header, after the class declaration, outside the namespace, I've included. But I really would like to know the correct way to solve this problem; one where it is not possible to modify. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries that are used. namespace CCS { Q_DECL_EXPORT Q_NAMESPACE. I read a bit and it seems that Q_DECLARE_SMART_POINTER_METATYPE is supposed to allow this to work. Call qRegisterMetaType() to make type available to non-template based functions, such as the queued signal and slot connections. I read a bit and it seems that Q_DECLARE_SMART_POINTER_METATYPE is supposed to allow this to work. Workaround: use a class. Q_DECLARE_METATYPE(Pkg) and this does not give compile errors, but in my main. To start viewing messages, select the forum that you want to visit from the selection below. It looks like one can register a type more than once, specifying different typenames, i. The ones I am registering for are mostly structs for storing data and just a few simple classes. I think it would be great if we could run requests in a QThread, but right now it's not possible because the r. It does not say anything about registering the type. qRegisterMetaType vs. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. I only care about runtime. QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). qRegisterMetaType vs. qRegisterMetaType vs. Now, that Q_DECLARE_METATYPE enables the type for Qt template classes and QVariant. Any class or struct that has a public constructor, a public copy constructor, and a public destructor can be registered. All I want to do is be able to convert this to a byte array in order to send on a socket, and get the object back (deserialize) on the other end. The reason to need this is usually that Q_PROPERTY is used with a metatype which is not built-in (types such as int and QString are built-in and don’t. See also disconnect(), sender(), qRegisterMetaType(), Q_DECLARE_METATYPE(), and Differences between String-Based and. Inheritance diagram of PySide6. waitForConnected ([msecs=30000]) # Parameters: msecs – int. To start viewing messages, select the forum that you want to visit from the selection below. Qt is throwing an exception because it doesn't know how to store the shared_ptr onto a QDataStream. A. I'm using Qt 5. 7. To start viewing messages, select the forum that you want to visit from the selection below. Call qRegisterMetaType () to make type available to non-template based functions. 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. 【2】使用方法（声明 和 注册自定义数据类型）. I haven't used that module yet but one thing you should do is remove the string argument from your qRegisterMetaType calls. Note: it's also safe to call qRegisterMetaType () multiple times. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. cpp I have to do: qRegisterMetaType<Pkg>("Pkg"); and this does not give errors too, but when I try to create a QVariant(Pkg) I get lots of errors like:cardio63 26 Jan 2016, 10:19. But this is all useless if you are not using templates. This allows us to use the Enum as a custom-type of a QVariant, to pass it between QML and Qt, to use it in synchronous signal-slot connections, and to print the symbolic enums (instead of a magic number) with qDebug(). : Q_DECLARE_METATYPE(MyClass*); That's how Qt handles it with QObject and QWidget. 1. Basically, I created a library containing a type: struct MyCustomType {. Specifically, the function have to be called before using the struct. Returns the used WebSocket protocol. At the point where I want to read the list, I only care about (and know) the fact that the list contains pointers to objects, which have been derived. See also state() and Creating Custom Qt Types. The file (called a "rep" file) uses a specific (text) syntax to describe the API. 2. A separate point for your own benefit. I've registered my class with: @Q_DECLARE_METATYPE(MyClass);@ and. qRegisterMetaType<Subclass> ("Subclass") also doesn't work. 4 which does not support all C++11 features. To start viewing messages, select the forum that you want to visit from the selection below. This results in access violations. qRegisterMetaType vs. 9k 9 34 52. QtCore. fromValue <QList<double> > ( x1); To copy to clipboard, switch view to plain text mode. h) of the derived class. There's no need to call qRegisterMetaType that many times, once is enough. . However, as you need the type to be. no unexpected garbage. When these files are processed by repc, repc generates both Source and Replica header files. enum Qt:: ContextMenuPolicycall qRegisterMetaType() to register the data type before you call QMetaMethod::invoke(). See also state() and Creating Custom Qt Types. You should use qmlRegisterType function for that. QMetaType::type () returns the same ID as qMetaTypeId (), but does a lookup at runtime based on the name of the type. Qt Base (Core, Gui, Widgets, Network,. If the type was not declared with Q_DECLARE_METATYPE (), compilation will fail. You may have to register before you can post: click the register link above to proceed. The Rep lica C ompiler (repc) generates QObject header files based on an API definition file. in a header file and call @qRegisterMetaType<std::unique_ptr<Thing>> ();@ before your signal and slots are used. Hello Ladies and Gentlemen. The code compiles and runs ok. qRegisterMetaType usage. Otherwise your signals and slots connected used the old mechanism (with macros SIGNAL and SLOT) that require queueing of the parameters won't know how to do so. [virtual] QAbstractSocket:: ~QAbstractSocket Destroys the socket. Unsure if my idea would work, I created a DataPoint class marked with Q_GADGET with three properties defined using Q_PROPERTY. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. Q_DECLARE_METATYPE. Call qRegisterMetaType() to register the data type before you establish the connection. Usually it goes in a pair: Q_DECLARE_METATYPE(TypeName) goes in the header, and then in the source at runtime registration is done with: qRegisterMetaType<TypeName>();answered May 10, 2013 at 2:25. . 3 Answers Sorted by: 13 "qRegisterMetaType" is a function. e. Don't use Q_DECLARE_METATYPE and qRegisterMetaType for your QObject enum. Call qRegisterMetaType () to make type available to non-template based. Avoid having to qRegisterMetaType (pointer. void QLocalSocket:: abort ()The Qt docs make it clear that to use a custom type with Queued Connections, I need to use both Q_DECLARE_METATYPE and qRegisterMetaType. J. Learn more about Teams I can't figure out a way to automatically declare a meta type, i. Q_DECLARE_METATYPE. So I am doing this: Qt Code: Switch view. 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. 1. Assuming base and derived are Q_GADGETs you want to get a static member. 1. You should use qmlRegisterType function for that. Tried proposed solution using QVariant::fromValue, but kept getting compiler errors of type: . Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. 手册中告诉我们，执行这个的时候，模板参数T必须用 Q_DECLARE_METATYPE() 声明过 能猜到原因吗？注意看前面 Q_DECLARE_METATYPE() 代码， 对了。类中的成员函数qt_metatype_id中包含对qRegisterMetaType(typeName)的调用 这儿就是辗转调用了这个带参数. 1. There's no such thing as a "const reference" because references are always const -- you can't reseat them. e. What is(are) the good place(s) to put the qRegisterMetaType call? I obviously don't want any expllicit. This also makes the type available for queued. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. [virtual] QAbstractSocket:: ~QAbstractSocket Destroys the socket. The struct is declared in my worker class, which is inside a namespace. no unexpected garbage. The following should work: Note that you also have to call qRegisterMetaType<MyMpiMessage> (); before you use the function the first time. 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. So using a QString as the type of a Q_PROPERTY only works because it has special built-in support in the QML engine. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. Jul 9, 2017 at 21:51. 4 which does not support all C++11 features. 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. Since Qt 5. I pass the MyClass pointer to the streaming operator and only stream things like QString, QPointF, etc. You have to register your class to Qt meta objects system. qRegisterMetaType vs. 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. Detailed Description. pro file, several errors appear referencing the QMouseEvent and QWheelEvent classes. Creating and Destroying Custom Objects 1 Answer Sorted by: 21 Objects are copied when put into a QVariant, but QObject derived classes cannot be copied, so the solution is to use a pointer to your class. Is your Q_DECLARE_METATYPE in a header file or an implementation file? Incidentally, there is a mistake in TreeItem. You should use Q_DECLARE_METATYPE macro for this. staticMetaObject is of type QMetaObject and provides access to the enums declared with Q_ENUMS. 3 to Qt4. See also state() and Creating Custom Qt Types. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. I'd understood if i want to pass my custom type like struct or so, but it is essential type. qRegisterMetaType<FileNodePointer> ("FileNodePointer"); should be called once (in main, constructor etc. 1、自定MyDataType 类型，在这个类型的顶部包含：#include <QMetaType>. I also added qRegisterMetaType<DataPoint> () to the initialisation method of my main. Q_DECLARE_METATYPE on the other hand is (as far as I know) preprocessor bound. However, if you want to use a type in a pure runtime context, for example in a QML document, the Qt runtime doesn't know the type declared with Q_DECLARE_METATYPE. Your code should look like this: Q_ENUM (StateEnum) //note the missing 'S' here Q_PROPERTY (StateEnum state READ state NOTIFY stateChanged) Share. Now, in your registerTypes function, it should be registered like this: qRegisterMetaType<AccReal > ("data::AccReal"); In other words, the typeName string must match exactly the type of the signal argument as it is written there. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. Jun 13, 2021 at 19:37. Join Date Mar 2010 Posts 69 Thanks 8 Thanked 1 Time in 1 Post Qt products Platforms} Q_DECLARE_METATYPE(Topic) In main, I have included this: qRegisterMetaType<Topic>("Topic"); When propagating these elements from c++ to QML, everything is working. I have a few instances of QVector<MyClass> which I want them to be exposed to QScriptEngine. 0. That always worked in Qt4, but in Qt5 I get the following error: @error: specializing member ‘::qRegisterMetaType<Subclass>’ requires ‘template<>’ syntax@. To register VideoMeta you need to call qRegisterMetaType<VideoMeta>(). 0. 2. You could try using registerConverter () to allow implicit conversion of the shared_ptr<int> to a regular int, and compare them that way. Q_DECLARE_METATYPE (T) requires the type T to be default-constructable, copiable and destructable. I have registered an enumeration type "ClefType" within my header file - this enum is registered with the MetaObject system using the Q_DECLARE_METATYPE and Q_ENUMS macros. Declare new types with Q_DECLARE_METATYPE () to make them available to QVariant and other template-based functions. It associates a type name to a type so that it can be created and destructed dynamically at run-time. g. due to requirements at my job, I had to revert by build from Qt5. The. Gerald Gerald. That was it for Q_DECLARE_METATYPE, but you would still need to call qRegisterMetaType to use these type in a Q_PROPERTY or as a parameter in a signal/slot queued connection. e. It does not say anything about registering the type. Labels: meta system, Meta type, qt. @Q_DECLARE_METATYPE (std::unique_ptr<Thing>);@. According to the Qt docs for qRegisterMetaType "Any class or struct that has a public default constructor, a public copy constructor, and a public destructor can be registered. 11. Research The QMetaType class manages named types in the meta-object system. The class in Qt responsible for custom types is QMetaType . 2 Answers. To start viewing messages, select the forum that you want to visit from the selection below. The QML engine provides built-in support for a. cpp. Now I want to read this property with Qt's meta object system. Q_GADGET makes a class member, staticMetaObject, available. 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. @Daddedebad As @Bonnie says qRegisterMetaType. Your Matrix type is not copiable, thus you can't use Q_DECLARE_METATYPE on it. I just tried. Using Qt 3D with QCustomPlot. h instead ofQVariant x2; x2. It seems that for a metatype that is a QList<MyClass::MyEnum> I must. Any class or struct that has a public default constructor, a public copy. 该类型必须有公有的 构造、析构、复制构造 函数. I need to call the Q_DECLARE_METATYPE() to pass the smart pointer. multithreaded software and I am getting the warning says: (Make sure 'QVector<int>' is registered using qRegisterMetaType (). To register a type, it must be declared as a meta-type with the Q_DECLARE_METATYPE() macro, and then registered as in the following example:. g. i. Make a typedef for QSharedPointer<UserDataType>, and use both Q_DECLARE_METATYPE as well as qRegisterMetaType () to register it for use. Output:Additionally Q_DECLARE_METATYPE and qRegisterMetaType are not purposed to be used for QObject derived classes. 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. To start viewing messages, select the forum that you want to visit from the selection below. 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。. It will return the same result if it was called before. As a workaround, I'm using QVariantMap instead of std::map. As you have already found out, you must use Q_DECLARE_METATYPE to make the type known to Qt. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries that are used. [override virtual] bool QLocalSocket:: waitForBytesWritten (int msecs = 30000) Reimplements:. 0. To start viewing messages, select the forum that you want to visit from the selection below. The QMetaType class manages named types in the meta-object system. J 1 Reply Last reply Reply Quote 0. If the pointer stored in the QVariant can be qobject_cast to T, then that result is returned. To start viewing messages, select the forum that you want to visit from the selection below. In short, I get following error: QObject::connect: Cannot queue arguments of type 'cv::Mat' (Make sure 'cv::Mat' is registered using qRegisterMetaType (). Also you may need to use qRegisterMetaType function. Posted by Unknown at 2:06 AM. until today. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. This function was introduced in Qt 4. void QAbstractSocket:: abort ()Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. 该类型必须有公有的 构造、析构、复制构造 函数. w/out GUI module you wouldn't have any of those types available). c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries. Secondly, your linker (MSVC) complains that it can't find the metaObject for your ErrorHandler enum, which is normal as it is not exported from the. no unexpected garbage data or the like). // This primary template calls the -Implementation, like all other specialisations should. What is(are) the good place(s) to put the qRegisterMetaType call? I obviously don't want any expllicit initialization. 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. Declare new types with Q_DECLARE_METATYPE () to make them available. qRegisterMetaType() docs say: Any class or struct that has a public constructor, a public copy constructor, and a public destructor can be registered. Constantin. Note: it's also safe to call qRegisterMetaType () multiple times. That was it for Q_DECLARE_METATYPE, but you would still need to call qRegisterMetaType to use these type in a Q_PROPERTY or as a parameter in a signal/slot queued connection. qRegisterMetaType vs. But there would be no trouble using the QMetaType class or using qRegisterMetaType before creating an instance of QCoreApplication or QApplication. qRegisterMetaType() requires also a Q_DECLARE_METATYPE() – dtech. 4] QString QWebSocket:: subprotocol const. Share. Share. ) summary refs log tree commit diff statsFoo and Foo* are different types and need to be registered separately. 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. 1 Answer. Please note that I do not use Q_DECLARE_METATYPE on purpose because I don't actually need its features (QVariant expansion) right now. Returns the internal ID used by QMetaType. The following code will work as well: using namespace foo; Q_DECLARE_METATYPE (MyClass) Teams. In general, you can only export two kinds of C++ types to QML: QObject-derived classes and some build-in value types, see this documentation page. [since 6. since it is a runtime registration. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. Also you may need to use qRegisterMetaType function. See also state() and Creating Custom Qt Types. Yes, templated types can be used in Qt signal/slots. This won't work because you can't use qMetaTypeId<> () before Q_DECLARE_METATYPE<>. The Q_DECLARE_METATYPE() macro and qRegisterMetaType() function documentation contain more detailed information about their uses and limitations. cpp. The "traditional" way of doing this is to convert each element to a QVariant, and pass collection as a QVariantList. As the docs state: Declare new types with Q_DECLARE_METATYPE () to make them available to QVariant and other template-based functions. . . void QLocalSocket:: abort ()The signal "orientationChanged" includes an enum of type "Orientation" to indicate if the card has been turned up or down. You may have to register before you can post: click the register link above to proceed. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. Type is not registered, please use the Q_DECLARE_METATYPE macro to make it known to Qt's meta-object system. It will return the same result if it was called before. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries. 5 is compiled with GCC 4. Q_DECLARE_METATYPE accepts objects with public constructor, copy constructor and destructor. the type name must be specified without the class, as in. I am also using some in queued signal and slot connections. 3. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. You may have to register before you can post: click the register link above to proceed. You may have to register before you can post: click the register link above to proceed. By the way, Qt 4. h" class Context : public QObject { Q_OBJECT Q_PROPERTY (MyGadget* gadget READ gadget CONSTANT) public: explicit Context () : QObject {nullptr} { } MyGadget* gadget () { return &_gadget; } private. 16. Declare new types with Q_DECLARE_METATYPE () to make them available to QVariant and other template-based functions. Share Improve this answerWe 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. I need to call the Q_DECLARE_METATYPE() to pass the smart pointer.