被 Q_DECLARE_METATYPEQ 标记的类型可以让Q MetaType 查询到类型，也可以让QVariant识别到。 struct MyStruct { QString name; }; Q_DECLARE_METATYPE(MyStruct) 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. Does your code ever call qRegisterMetatype() or use Q_DECLARE_METATYPE()? 10th November 2014, 05:23 #3. Here you can see that the macro expands to nothing. 4 and it seems to work. call qRegisterMetaType with the name specified, else reading properties. I explicitly don't want to update it on every change to one of the quantities, so they don't. 4. due to requirements at my job, I had to revert by build from Qt5. Returns the internal ID used by QMetaType. Obviously then you would not do registerComparator (). Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. You may have to register before you can post: click the register link above to proceed. 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. 3 to Qt4. 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. To start viewing messages, select the forum that you want to visit from the selection below. 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. Any idea what I'm missing please? BTW, no problem at all using Schedule in QMetaProperty or QVariant. 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. Couple of points: 1) I would use QScriptEngine::newObject() instead of newQObject() for the namespace 2) I would not use a QObject subclass for the data entry if possible, only the prototype has to be. 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. It associates a type name to a type so that it can be created and destructed dynamically at run-time. In fact, all Qt classes derived from QObject (direct or indirect) use this macro to declare their copy constructor and assignment operator to be private. 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. The Custom Type and Queued Custom Type examples show how to implement a custom type with the features outlined in this document. Normally, you would only register the pointer form if your class cannot be copied, as in the case of QObject and derivatives, but. If you ever wondered what does Q_DECLARE_META_TYPE or qRegisterMetaType do and when to use (or not to use) them, read on. 总之，有时候，我们多么希望信号能发送自定义数据类型。. 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 (). Of course it's a bug and an odd mistake that Q_DECLARE_METATYPE(QList<QSslError>) is in qsslsocket. QMetaType::type () returns the same ID as qMetaTypeId (), but does a lookup at runtime based on the name of the type. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. akshatrai91 7 Jan 2021, 06:21. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. There's no need to call qRegisterMetaType that many times, once is enough. QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). The QMetaType class manages named types in the meta-object system. 3. Using the Q_DECLARE_METATYPE () macro 2. 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. Call qRegisterMetaType() to make type available to non-template based functions, such as the queued signal and slot connections. JulienMaille @kshegunov last edited by JulienMaille . So using qRegisterMetaType () you will just trade Q_ENUM () for Q_DECLARE_METATYPE (). I have an application that requires use of both Qt 3D and the QCustomPlot library. QtCore. Don't use Q_DECLARE_METATYPE and qRegisterMetaType for your QObject enum. To make the custom type generally usable with the signals and slots mechanism, we need to perform some extra work. 该类型必须有公有的 构造、析构、复制构造 函数. Any class or struct that has a public default constructor, a public copy constructor, and a. 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. In the example's Message class, a static method is included to do this. void QLocalSocket:: abort ()The signal "orientationChanged" includes an enum of type "Orientation" to indicate if the card has been turned up or down. First of all, you always need to declare your meta type: Q_DECLARE_METATYPE (foo::MyClass) It works at compile time, so there are no limitations on how you refer to your class. This function was introduced in Qt 5. 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. Note: it's also safe to call qRegisterMetaType () multiple times. Any class or struct that has a public constructor, a public copy constructor, and a public destructor can be registered. Call qRegisterMetaType () to make type available to non-template based. You may have to register before you can post: click the register link above to proceed. Additionally Qt5 always refers to Q_DECLARE_METATYPE, saying that qRegisterMetaType is only when you want to. Q_DECLARE_METATYPE vs qRegisterMetaType for non global namespace classes. 0. Any class or struct that has a public default constructor, a public copy constructor, and a public destructor can be registered. 2. Ah, sorry, I didn't noticed that part. Q_DECLARE_METATYPE(MyClass); qRegisterMetaType<MyClass>(); I can use the type in queued connection with signals like this one: void MySignal(MyType o); Now I also would like to use the type with signals like this: void MyVectorSignal(QVector<MyType> v);Qt 5. EDIT: When you convert your class to QVariant it uses a. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. 1 Answer. 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. genC last edited by . This may make certain type comparisons fail. [edit] forgot to mention that you also have to use a worker object. qRegisterMetaType you'll need if creating objects by class name dynamically, and it seems for queued connections,. The QMetaType class manages named types in the meta-object system. There's also no need for that typedef, it only makes the code less readable. To enable using the type in queued signals and such, there also needs to be a corresponding call: qRegisterMetaType<foo::FooState>(); Question. I my real world application Context holds a large number of physical quantities (masses, forces, velocities,. " Yet types like QVariantMap are themself typedefs. Q_DECLARE_META_TYPE (Fruit) and qRegisterMetaType were redundant: #define PluginInterface_iid "pluginInterface" Q_DECLARE_INTERFACE (PluginInterface, PluginInterface_iid) //Actual plugin implementing PluginInterface class. You may have to register before you can post: click the register link above to proceed. QMetaType::type () is a bit slower, but compilation succeeds if a type is not registered. Detailed Description The QMetaType class manages named types in the meta-object system. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries. 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. e. Remember that Q_DECLARE_METATYPE merely defines a specialization of QMetaTypeId for your type. cpp. As the docs state: Declare new types with Q_DECLARE_METATYPE () to make them available to QVariant and other template-based functions. It does not say anything about registering the type. Email This BlogThis! Share to Twitter Share to Facebook Share to Pinterest. It associates a type name to a type so that it can be created and destructed dynamically at run-time. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. [quote author="Andre" date="1306394817"]In that case, I think you need to register them. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. Call qRegisterMetaType () to make types available to non-template based functions, such as the queued signal and slot connections. First of all you need to declare your custom object for Qt metatype system. You should use Q_DECLARE_METATYPE macro for this. Also, Q_DECLARE_METATYPE(MyNamespace::MyType) should be in the header declaring MyType so that you don't have to repeat it all over again and again. Research The QMetaType class manages named types in the meta-object system. jsulm Lifetime Qt Champion @shivaVMC last edited by . This function is useful to register typedefs so they can be used by QMetaProperty, or in QueuedConnections. fromValue <QList<double> > ( x1); To copy to clipboard, switch view to plain text mode. I think you need to add an explicit export/import directive to the QT_NAMESPACE macro. To copy to clipboard, switch view to plain text mode. It associates a type name to a type so that it can be created and destructed dynamically at run-time. It was also no big issue to call qRegisterMetaType () automatically. }; Q_DECLARE_METATYPE (MyCustomType); Then in my application, I have a signal "void sendMsg (MyCustomType)" and I qRegisterMetaType (). 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. F. With Q_DECLARE_METATYPE and without qRegisterMetaType: No warning, slot is called With Q_DECLARE_METATYPE and with qRegisterMetaType: No warning, slot is called. Actually, they are declared, but in a private section with the macro Q_DISABLE_COPY(). The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. The class is used as a helper to marshall types in QVariant and in queued. I am also using some in queued signal and slot connections. It is a static method, it does not (cannot) change x2. I. Obviously, a call to qRegisterMetaType<T>(. So I tried declaring the following at end of my worker thread class Q_DECLARE_METATYPE(cv::Mat);. You could try using registerConverter () to allow implicit conversion of the shared_ptr<int> to a regular int, and compare them that way. It manages an insane amount of static variables and sets a static global pointer of. You can register a class pointer as the metatype, though. Consider the specific case of qRegisterMetaType. . 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. From the QVariant::value documentation: If the QVariant contains a pointer to a type derived from QObject then T may be any QObject type. qRegisterMetaType() docs say: Any class or struct that has a public constructor, a public copy constructor, and a public destructor can be registered. 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. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. typedef QVector<QSharedPointer<Tester> > TestPointerVector;. The class is used as a helper to marshall types in QVariant and in queued. 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. But at run time, I got below error:1 Answer. Q_DECLARE_METATYPE, as pointed out by @SingerOfTheFall, would register template based type into QVariant (so it can be retrieved using qvariant_cast<T>()). Q_DECLARE_METATYPE(TYPEDEF) Q_DECLARE_METATYPE(TYPEDEF) mainwindow. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. Q_DECLARE_METATYPE (T) requires the type T to be default-constructable, copiable and destructable. See also Thread Support in Qt, QObject::connect(), qRegisterMetaType(), and Q_DECLARE_METATYPE(). Declare new types with Q_DECLARE_METATYPE () to make them available. One way to work around this is for example having a helper class (singleton or context property) with. qRegisterMetaType vs. enum Qt:: ContextMenuPolicycall qRegisterMetaType() to register the data type before you call QMetaMethod::invoke(). After googling this, I found this correspondence, which was only available through a third party archival site as google. As you already have a typedef for your type, you can simply use Q_DECLARE_METATYPE as in the following example: #include <QtCore> template <typename T> struct Proxy { T data; }; typedef Proxy<QImage> TrayType; Q_DECLARE_METATYPE (TrayType) class Donor : public. the type name must be specified without the class, as in. Actually, they are declared, but in a private section with the macro Q_DISABLE_COPY(). From the docs: int qRegisterMetaType ( const char * typeName ) Registers the type name typeName to the type T. So you can call it from your constructor. To use the type T in queued signal and slot connections,. // This primary template calls the -Implementation, like all other specialisations should. e. Some structure need to be registered to be queued in asynchronous signals using qRegisterMetaType<T>(name), such as signal which passes QVector<int>. since it is a runtime registration. ) is supported. qRegisterMetaType vs. 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. To enable using the type in queued signals and such, there also needs to be a corresponding call: qRegisterMetaType<foo::FooState>(); Question. [virtual] QLocalSocket:: ~QLocalSocket Destroys the socket, closing the connection if necessary. Using the macro directly turned out to be impossible. 0. QMetaType registerNormalizedTypedef normalizedTypeName, type: metaType ); return. This replaces the now-deprecated Q_ENUMS and will automatically register the metatype. Qt Base (Core, Gui, Widgets, Network,. I store them in QVariant :. Q_GADGET makes a class member, staticMetaObject, available. qRegisterMetaType is also called in the class constructor. ) summary refs log tree commit diff stats Foo and Foo* are different types and need to be registered separately. 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. complains that the metatype isn't registered. namespace CCS { Q_DECL_EXPORT Q_NAMESPACE. 6. 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. x however, the code generated by moc will call qRegisterMetaType for you if moc can determine that the type may be registered as a. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. Declare new types with Q_DECLARE_METATYPE () to make them available. Share. 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. That's probably there, as qRegisterMetaType () wouldn't compile otherwise. Also Q_DECLARE_METATYPE does not register a type, but declares it. [override virtual] bool QAbstractSocket:: waitForBytesWritten (int msecs = 30000) Reimplements:. There's no compile time error, but when I run. The macro will register your variable with the Qt Meta-Object System, which will allow you to. You should use qmlRegisterType function for that. 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. QLocalSocket. Note that you are technically lying to the meta type system. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. In the header, after the class declaration, outside the namespace, I've included. Re: How to use Q_DECLARE_METATYPE. So my first idea:. Type is declared with Q_DECLARE_METATYPE and registered with qRegisterMetaType. QVariantList MyClass::getFooCollection (void) const { QVariantList list; for (const auto& l: fooCollection_) { list. The Problem: I want to create an object instance at runtime using QMetaType by the type name. 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. You can't with Q_GADGETS. To enable creation of objects at run-time, call the qRegisterMetaType() template function to register it with the meta-object system. uint64; If this is your first visit, be sure to check out the FAQ by clicking the link above. To start viewing messages, select the forum that you want to visit from the selection below. g. 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. I guess it's the qRegisterMetaType () call itself that's missing. 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. wysota. [override virtual] bool QLocalSocket:: waitForBytesWritten (int msecs = 30000) Reimplements:. Tried proposed solution using QVariant::fromValue, but kept getting compiler errors of type: . The class is used to send arguments over D-Bus to remote applications and to receive them back. // - in a header: // - define a specialization of this template calling an out-of. See also isRegistered () and Q_DECLARE_METATYPE (). I created a. Re: Qt warning of type conversion already registered Originally. I have a const pointer to a class derived from qobject and want to put into QVariant like below: QVariant::fromValue(objectPointer) I have declared the meta type of derived class using: Q_DECLARE_METATYPE(const QDrivedClass *) in the header file (. Any class or struct that has a public constructor, a public copy constructor, and a public destructor can be registered. The QMetaType class manages named types in the meta-object system. 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. The same plugin may be loaded multiple times during the application's lifetime. 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. Passing across threads (queued connection) will copy the QVector in either case, but the const will remind you that you cannot alter the original QVector in. Q_DECLARE_METATYPE. Re: How to use Q_DECLARE_METATYPE. That. The Rep lica C ompiler (repc) generates QObject header files based on an API definition file. Posted by Unknown at 2:06 AM. Re: Qt warning of type conversion already registered Originally. Well, I certainly overplayed this particular point, but the statement I believe is valid in principle. How: I linked qRegisterMetaType. QLocalSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. Call qRegisterMetaType() to make types available to non-template based functions, such as the queued signal and slot connections. Use Q_DECLARE_METATYPE (std::string) in one of your headers. 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. Teams. 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. qRegisterMetaType () is called to register the TYPE and generate a TYPE ID. For that, I want to declare a. Make sure you call it from within a method. Using the following required me to use Q_DECLARE_METATYPE. If I get AnotherQGadgetClass via getter and change it's properties, the setters are called and. 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. i. QML_DECLARE_TYPE. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. on top of main. Compares this QVariant with v and returns true if they are equal;. 基本理解. 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. This requires the exchanged data to be of a type that is recognizable by the engine. :) QApplication is the root QObject of the program and its full initialization is required before anything can practically be done with anything else. Workaround: use a class. The file (called a "rep" file) uses a specific (text) syntax to describe the API. This object can then be passed from QML to C++ via. 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. One of these plugins uses Q_DECLARE_METATYPE on some types that need to be stored in a QVariant. ", which suggests it is only for classes and structs. 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(). Please note that I do not use Q_DECLARE_METATYPE on purpose because I don't actually need its features (QVariant expansion) right now. In some cases in Qt 4, it is also necessary to use the qRegisterMetaType method. 1 Answer. said, try to directly pass shared_ptr with your signal/slots. I tried to write one, but I failed. Franzk 26 May 2011, 06:59. The other overload around has almost the same form but for the. h" class B : public QObject { Q_OBJECT Q_PROPERTY(A* A1 READ getA1 WRITE setA1) Q_PROPERTY(A* A2 READ getA2 WRITE setA2) public: static A A1;. This also makes the type available for queued. By convention, these files are given a . See also state() and Creating Custom Qt Types. 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. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. To register. I've registered my class with: @Q_DECLARE_METATYPE(MyClass);@ and. See the Custom Type Example for code. Declare new types with Q_DECLARE_METATYPE() to make them available to QVariant and other template-based functions. There is no way to add support for more of these value types like std::string (*). . Also, to use type T with the QObject::property () API,. Returns true if convert can convert from fromType to toType. [virtual] QAbstractSocket:: ~QAbstractSocket Destroys the socket. To start viewing messages, select the forum that you want to visit from the selection below. I haven't used that module yet but one thing you should do is remove the string argument from your qRegisterMetaType calls. Qt is throwing an exception because it doesn't know how to store the shared_ptr onto a QDataStream. Since Qt 5. 23k 10 10 gold. 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(). Read and abide by the Qt Code of Conduct. class Test : public QWidget { Q_OBJECT public: Test(); signals: public slots: void setAppData(QList<QIcon> icons, QStringList names, QStringList versions, QStringList publishers, QString installLocation, QStringList uninstallLocations); private: }; Q_DECLARE_METATYPE(QIcon) The same issue is still present. I need to call the Q_DECLARE_METATYPE() to pass the smart pointer. staticMetaObject is of type QMetaObject and provides access to the enums declared with Q_ENUMS. To start viewing messages, select the forum that you want to visit from the selection below. cpp. Because Foo is not derived from QObject and QVariant only supports polymorphism for QObject -derived types. Got a similar example working without explicitly calling qRegisterMetaType() just by removing the semicolon from the line Q_DECLARE_METATYPE(StateMachine::state) – user666412 Sep 21, 2015 at 14:17Additional types can be registered using qRegisterMetaType() or by calling registerType(). See QMetaType docs for more information. Q_DECLARE_METATYPE(TYPEDEF) Q_DECLARE_METATYPE(TYPEDEF) mainwindow. private: AnotherQGadgetClass test_; } Q_DECLARE_METATYPE(QGadgetClass) I am trying to access Q_GADGET from QML classic way like accessing a Q_OBJECT , but the setters are not called. 2、在类型定义完成后，加入声明：Q_DECLARE_METATYPE (MyDataType); 3、在main ()函数中. So you can call it from your constructor. type() typeName() PySide6. qRegisterMetaType 必须使用该函数的两种情况. Don't use Q_DECLARE_METATYPE and qRegisterMetaType for your QObject enum. Sorted by: 1. When using signals and slots with multiple threads, see Signals and Slots Across Threads. Adding a Q_DECLARE_METATYPE() makes the type known to all template based functions, including QVariant. Qt is throwing an exception because it doesn't know how to store the shared_ptr onto a QDataStream. 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 class is used as a helper to marshall types in QVariant and in queued signals and slots connections. When the plugin is reloaded later, the old declaration still points to the original memory space of the now-unloaded library. @SGaist Yes, I am using it with QVariant, mostly with QSettings to save and retrieve data easily by overriding QDataStream operators. @Q_DECLARE_METATYPE (std::unique_ptr<Thing>);@. See also state() and Creating Custom Qt Types. c:55 This looks like some loader initialization mismatch, check debug vs release builds of your application and libraries that are used. 5 is compiled with GCC 4. See the Qt D-Bus Type System page for more information on the type system. Using Q_ENUM () allows you to retrieve at run-time. container. type() typeName() PySide6. Q_DECLARE_METATYPE (std::string) Quoting Qt Doc. Qt. This also makes the type available for queued. Avoid having to qRegisterMetaType (pointer. It is often easier and cleaner to define an ENUM inside a class (see ENUM), but if you need a standalone enum type, using the ENUM keyword outside of a class definition can be. The object it returns should also be a member of the factory class. Accessing an enum stored in a QVariant. To use the type T in queued signal and slot connections, qRegisterMetaType<T>() must be called before the first connection is established. It's not enough to get reflection features out of a type this way (it does not create a QMetaObject), so for the thing to be useful at all you need at least Q_GADGET in both base and derived classes. You can also use QMetaEnum::fromType() to get the QMetaEnum. 1. // This primary template calls the -Implementation, like all other specialisations should. The logical equivalent of a const T &r (reference to const T) is a const T * const p (const pointer to const T). You may have to register before you can post: click the register link above to proceed. 0. hpp and qRegisterMetaType<quint32>("quint32"); in both the Constructors of Class1 and Class2. I'm trying to use custom classes in QAbstractListModel, and the Q_DECLARE_METATYPE doesn't work at all! To test where the problem is, I've simplified the code as the following: #include <QMetaType> #include <QVariant> #include <QDebug> typedef int x; Q_DECLARE_METATYPE (x) void main () { QVariant v; qDebug () << v. ) I have defined MyStruct in an accessible header file: myheader. 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. QVariant v = QVariant::fromValue<cMyClass>(MyObject); However, as soon as I use Q_DECLARE_METATYPE, I get errors about using a deleted function. To start viewing messages, select the forum that you want to visit from the selection below. I believe this is related to the fact that. See also. Has anyone else encountered this?See also qRegisterMetaType(). qRegisterMetaType 必须使用该函数的两种情况. Yes I tried with qRegisterMetaType, it. " Currently I have no UI implemented (yet!). このケースでも、Q_DECLARE_METATYPE(QSharedPointer<MyObject>)の宣言と、qRegisterMetatype<QSharedPointer<MyObject>>()の呼び出しが必要になる。 上のサンプルでは、同じsignalに対して2回connectを実行している。The same plugin may be loaded multiple times during the application's lifetime. 2. An alternative would be to wrap shared_ptr<int> in your own class and implement comparison the way you want. QDBusArgument is the central class in the Qt D-Bus type. Thank you Volker, I had a couple of problems I forgot about the Q_DECLARE_METATYPE(myType); and I don't' think I was never consistent with the global scope specifier. This function was introduced in Qt 6. Sorted by: 2. To make the custom type. By the way, Qt 4. There's no need to call qRegisterMetaType that many times, once is enough. Returns the internal ID used by QMetaType. When the plugin is reloaded later, the old declaration still points to the original memory space of the now-unloaded library. [virtual] QLocalSocket:: ~QLocalSocket Destroys the socket, closing the connection if necessary. See also state() and Creating Custom Qt Types. 24th July 2010, 09:54 #6. goocreations 12 Mar 2013, 07:22. If you need the functionality provided by Q_DECLARE_METATYPE, you will have to use it. ompiler (repc) generates header files based on an API definition file. Alt. int videoSourceMetaTypeId = qRegisterMetaType< VideoSource > ();QAbstractSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType(). G. 7. See also. Type is not registered, please use the Q_DECLARE_METATYPE macro to make it known to Qt's meta-object system. @Mark81 Actually you'll probably need only Q_DECLARE_METATYPE as this is done at compile time - exposing the type to the metatype system (I know it is an enum but it's needed for the QVariant and the like). Learn more about Teams Declaring a meta type. QtCore. 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. The default access for a class is private, so that Container* data();. That said, your stack trace is really strange: _dl_debug_initialize (ldbase=4294967292, ns=1095236752) at dl-debug. Call qRegisterMetaType<std::string> (); in the initialization of your code. This is not the case, since the following succeeded: @QMetaType::type("MyClass"); // success@.