This is easy enough as the following example demonstrates: //. Hi all. Thanks for contributing an answer to Stack Overflow! Please be sure to answer the question. rootContext (). Pulling References from QML. 0 because in qmlRegisterType, I passed the parameters 1 and 0) You can now add your C++ class to the QML File. git. Meta type. You must pass a name under which the object will be accessible and the pointer to a QML object. qml, to hold our UI definition in QML. Qt Project Git Repository Browser: Code less. 4. QObject is the base class for all Qt classes, Q_OBJECT macro is used to enable meta-object features in classes and finally moc is a preprocessor that changes Q_OBJECT macro instances to C++ source code to enable. void Component:: addAutoDependOn (const QString & newDependOn) Adds the component specified by newDependOn to the automatic depend-on list. This means, for instance, that you can have introspection support for enumerations defined in a namespace (not just in QObject subclasses, or classes tagged with Q_GADGET), and use such enumerations in QtScript, QtDBus and QML. You can vote up the ones you like or vote down the ones you don't like, and go to the original project or source file by following the links above each example. Dynamically instantiating a QML object from C++ is well documented, but what I can't find is how to instantiate it with pre-specified values for it's properties. Contribute to dliess/Push2Control development by creating an account on GitHub. cppThe c++ (cpp) qmlregisteruncreatablemetaobject example is extracted from the most popular open source projects, you can refer to the following example for usage. QML extension plugins are for either application-specific or library-like plugins. First, we have to declare an enum inside a . I think createQmlObject is a larger overkill but anyway I didn't mean to use createComponent. 所以我们不能在qml文件中为类创建对象，但是我们可以在qml文件中使用属性ans枚举类型属于这个类。. QNetworkAccessManager is used for all network access by QML. There is the AUTOMOC_MACRO_NAMES target property you can set, but we should probably add Q_NAMESPACE to the default set. I create a new Qt Quick 2 project and add the following contents: #Add more folders to ship with the application, here folder_01. But [QMetaProperty::read: Unable to handle unregistered datatyp. Note that the value returned by this function is the QDebug object itself, though this is often obtained by calling the maybeSpace() member function of QDebug that pads out the stream with space characters to make it more readable. 2 import QtQuick. Qt provides a range of standard value types that are used to provide rich and meaningful APIs. Qt's meta-object system provides the signals and slots mechanism for inter-object communication, run-time type information, and the dynamic property system. Next, we declare a custom QObject, just like in the overview, but this time it derives from QQuickItem. First, right-click the C++ “Sources” folder of your project in Qt Creator, select “Add New…” and choose the “C++ Class” template in the C++ section: 3. setContextProperty. For more information on accessing QML objects. This index is called internally the relative index. You can also simply use rust type String, but using QString might avoid unecessary conversions in some case. Among other things, meta-object code is required for the signals and slots. However, as a compiler- and platform-independent library, Qt does not rely on non-standard compiler features like __property or [property]. Select Assign, and then select OK . git. If instead the enum is placed into a QObject derived class and the class type is registered in the same way using qmlRegisterType () then the QML editor provides autocomplete for the enum values, but. For instance I have enum from thirdparty library: namespace Lib { enum class Foo { Bar, Baz }; }; I have tried use next wrapper namespace Qml { Q_NAMESPACE using Foo = Lib::Foo. To run the example application, you first need to set up a secure CoAP server. Said class is used on a single QML page (though this might change in future), and so I attach it with qmlRegisterType based on this recommendation in the docs. Contribute to Malibushko/nure_timetable development by creating an account on GitHub. Qt Creator: 4. ** accordance with the commercial license agreement provided with the. Also, remember that QML does not quite understand enums, if you want to store it in QML you need to use int. Contribute to GIPdA/DynamicMetaobject development by creating an account on GitHub. Sets the factory to use for creating QNetworkAccessManager (s). I think it wasn't found because my type (I have registered with qmlRegisterType) is not an Item-derived object. Hilk Moderators about 10 hours ago @sierdzio. Attributes in Object Declarations. VRonin 27 Apr 2021, 07:29. pragma Singleton import VPlayApps 1. The presence of the CONSTANT attribute indicates that the property value is constant. If it represents a type, it returns QMetaType::Int. 5 import miniModel. cpp" for registering C++ to QML. 7. If you're using qmake, create a qmldir file to describe the plugin. 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(). Sorted by: 1. Qt5 C++ GUI Programming Cookbook, Second Edition teaches you how to develop functional and appealing user interfaces using the latest version of QT5 and C++. 3 -. subVersion 使用qmlRegisterType进行qml类型的注册 第一步、建立C++类 Hello. void MyPackagePlugin::registerTypes(const char *uri) { using namespace facelift::example::mypackage; // Register generated. cpp. I had the exact same issue. Declare new types with Q_DECLARE_METATYPE () to make them available to. The set of QML object-type attribute types is as follows: the id attribute. The re-exported crate qttypes contains binding to the most usefull basic types such as QString, QVariant,. Create a file alongside main. This page contains a comprehensive list of all new classes and functions introduced in Qt 5. Now I want to get the class name from this object. The solution is to always work on Q_OBJECTs with pointers. You can declare properties of an uncreatable type in a C++ type declaration only. In the case of this enum, which essentially aliases the int type, it will simply mean that the. In this case, the root object is a Rectangle, so any properties, methods and signals of Rectangle are made available, allowing application. If it finds one or more class declarations that contain the Q_OBJECT macro, it produces a C++ source file containing the meta-object code for those classes. 1 Answer. controls 2. 2 there is, for the first time, a comprehensive build system API that allows you to specify a QML module as a complete, encapsulated unit. 6. QML HTTP GET request. The errors you are getting are making it clear that it wouldn't work with const anyway you twist it, because that's not how the API is designed, because while you can pass non-const objects to const functions, you cannot do the opposite for reasons that should be obvious. The console. Until then you have to use qt5_wrap_cpp(moc_file ns. In syntactic terms, a QML object type is one which can be used to declare an object by specifying the type name followed by a set of curly braces that encompasses the attributes of that object. name> to specify the import name. qml as shown below. 9 import QtQuick. 453. Step 2 (meta type Declare macro), if needed, describe your custom type/class to things like QVariant, QDebug and other "support" systems used everywhere on QObjects. This attribute was introduced in Qt 6. Then instantiate your class object and expose it in main. . I was wondering about the behaviour of the registered type with the qml engine. The QTransform component is not shareable between multiple QEntity 's. Alternatively, multiple components can be specified by separating each with a comma. 13. qqmlengine. git. New Functions in Namespaces. I had the exact same issue. To find out the IP address of a docker container, first retrieve the container ID by running the docker ps command, which will output something like: $ docker ps CONTAINER ID IMAGE 5e46502df88f sokurazy/coap-secure-test-server:californium. I have a QObject derived class Expense that I use in QML like this. The Qt QML module provides both a. mzimmers @mzimmers 9 days ago. maxImplicitWidth(children) implicitHeight: LayoutUtils. This tutorial shows how to write a QML extension using C++ that includes core QML features, including properties. Yes, all communication between C++ and QML is based on QVariants. struct package_manager { static constexpr auto package_name = "com. The object it returns should also be a member of the factory class. Created the qml type in a qml document. invoke(this); And let Qt handles the call to activate(). Asking for help, clarification, or responding to other answers. 0 Object {} So now you have a QML source wrapper to create the C++ Object dynamically. Create ("Your Type"); It is not perfect but satisfied my requirement. Kyeiv @sierdzio 1 Jul 2021, 04:12. . log("a"); } } Item { id: item2. Commit 4772476 by @sztomi rightfully imports qml_register_enum in the prelude, but qml_register_enum only gets generated on Qt 5. To find out the IP address of a docker container, first retrieve the container ID by running the docker ps command, which will output something like: $ docker ps CONTAINER ID IMAGE 5e46502df88f sokurazy/coap-secure-test-server:californium. 5 import miniModel. createQmlObject (): failed to create object: Non-existent attached object: use Repeater in your GridLayout to create the items you need. Fooindex: qt-creator/qt-creator. ompiler: MSVC2019 64Bit. 8] void QQmlEngine:: exit (int retCode) This signal is emitted when the QML loaded by the engine would like to exit from the event loop with the specified return code retCode. For more information on accessing QML objects. Add: CONFIG += qmltypes to instruct the build system to generate QML types. qml called images. This is a significant improvement, but as the concept of QML modules was rather under-developed in Qt 5, even seasoned QML developers might now ask "What exactly is a. medtronic. 1. The element name should start with Capital Letter. import QtQuick 1. Create an empty folder alongside the main. Re: objectName property doesn't work as expected in C++ defined QML classes. QVariants are important in QML because they used to store the arguments from signals and slots, and also get values from the QMetaProperty system. Create an empty folder alongside the main. rootObjects (). Due to the tight integration of the QML engine with the Qt meta-object system, any functionality that is appropriately exposed by a QObject -derived class or a Q_GADGET type is accessible from QML code. var test = CppCreator. This maintains their identity, and avoid copies. To write a QML extension plugin: Subclass QQmlEngineExtensionPlugin and use the Q_PLUGIN_METADATA () macro to. [since 5. and another folder with the obj files. def disconnect (sender, signal_index, receiver, method_index. Inside your clock folder create an empty file named main. 7 I've found some examples of qmlRegisterType on the internet but just can't make it work. So, replace your line QMetaObject::activate(. def checkConnectArgs (signal, method). The QObject class is the base class of all Qt objects. Toggle Light / Dark / Auto color theme. git. The Qt QML module provides both a. h #ifndef ENUMCLASSES_H #define ENUMCLASSES_H #include <QObject> namespace mynamespace { enum class Fruit : int { Apple, Banana, Orange }; Q_ENUM (Fruit) } #endif // ENUMCLASSES_H. Method 1: Passing the root object. To write a QML extension plugin: chrisadams 17 Mar 2013, 17:19. The transformation is held as QVector3D scale, QQuaternion rotation and QVector3D translation components. One of the strengths of QML and C++ integration is the ability to implement UIs in QML separate from the C++ logic and dataset backend, and this fails if the C++ side starts manipulating QML directly. Inside your clock folder create an empty file named main. For more information on accessing QML objects. A QItemSelectionModel keeps track of the selected items in a view, or in several views onto the same model. enums", // import statement 1,0, // major and minor version. C++ and QML approach. The reason I was seeing a difference between Q_OBJECT and Q_GADGET was that I was making copies of my object, which is allowed on a Q_GADGET (a value) object, but not on a Q_OBJECT (an identity object. Call qRegisterMetaType () to make types available to non-template based functions, such as the queued signal and slot connections. class MyClass : public QObject { Q_OBJECT Q_PROPERTY (Priority priority READ priority WRITE setPriority NOTIFY priorityChanged) public: MyClass (QObject *parent = nullptr); ~MyClass (); enum Priority { High, Low, VeryHigh, VeryLow }; Q_ENUM (Priority) void setPriority (Priority priority) { m. 13. You can connect a signal to a slot with connect (). mode = mode is the correct syntax. The set of QML object-type attribute types is as follows: the id attribute. This type of connection can cross the date line in the longitudinal. I meant Q_DECLARE_METATYPE(application::BookOperationStatus) but it probably does not apply in this case. To register a QObject -derived class as an instantiable QML object type, add QML_ELEMENT or QML_NAMED_ELEMENT (<name>) to the class declaration. -** a written agreement between you and The Qt Company. 8. Some of the values work fine but others give undefined value. The Object and List Property Types example shows how to add object and list properties in QML. Yes i do. If you don't want to add your enum to a class with Q_OBJECT or Q_GADGET, then the other way to do it is to put your enum inside a Q_NAMESPACE. git. . b",1,0,"c"); and import a. These extensions allow custom QML types to be made available to the QML engine. index: qt-creator/qt-creator. py. An import statement allows clients to tell the engine which modules, JavaScript resources and component directories are used within a QML document. There are several methods to modify a property of a QML element from python/C++, and each has its advantages and disadvantages. h - pass around objects of this type between C++ and QML. This function was introduced in Qt. Note that CMake will, by default, automatically generate the qmldir file. Subclass QQmlEngineExtensionPlugin and use the Q_PLUGIN_METADATA () macro to register the plugin with the Qt meta. target = qml DEPLOYMENTFOLDERS =. I use qmlRegisterType<_> ("a. int qmlRegisterInterface ( const char * uri, int versionMajor) 451. This is enough for our basic QML setup. There are downsides to this approach: You always need to keep your type registrations in sync with the actual types. Select the Press shortcut keys field and press your preferred keys to add them to the field. They do not include the indexes of the parents. . Contents: Overview. Obtain the QML object through findChildren through another object. root->metaObject ()->className ()If this is your first visit, be sure to check out the FAQ by clicking the link above. Select Assign, and then select OK . py and main. Then you can obtain the IP address with the following command:Problem I'm trying to register a namespace in QML from a shared library, but the compilation fails with an unresolved external symbol error: failed (exit code 1120) with the following output: main. I applied Material Dark Theme on my application as recommended on this question: main. QxOrm is developed by Lionel Marty, a software development engineer since 2003. It also declares an object hierarchy that will be instantiated should an instance of. qml import Object 1. setContextProperty ("rootObject", QVariant::fromValue (engine. ** ** $QT. I create a new Qt Quick 2 project and add the following contents: This is. Signals and slots are made possible by Qt's meta-object system. qml, to hold our UI definition in QML. The presented code does the following: <1> Create object of QObject derived class and expose it to QML. qml import QtQuick Item { propertyintsomeNumber:100 } The value of the someNumber property can be set and read using QQmlProperty, or QObject::setProperty () and QObject::property ():Qt’s meta-object system provides the signals and slots mechanism for inter-object communication, run-time type information, and the dynamic property system. qml Expense { id: expenseManager onExpenseCreated: { // Do something } } The expense class has no UI components, it has some basic Signal and Slots for API communications. So Qt. index: qt-creator/qt-creator. This QML file looks like this: import QtQuick 2. The set of QML object-type attribute types is as follows: the id attribute. hpp : #ifndef STYLE_HPP #define STYLE_HPP #include <QtGlobal> #if QT_VERSION < QT_VERSION_CHECK(5,0,0) // Qt 4 #include <QDeclarativeEngine> #else // Qt 5 #include <QQmlEngine> #endif // Required derivation from QObject class StyleClass : public QObject { Q_OBJECT public: // Default constructor. Stack Overflow is leveraging AI to summarize the most relevant questions and answers from the community, with the option to ask follow-up questions in a conversational format. If it finds one or more class declarations that contain the Q_OBJECT macro, it produces a. 15. This example adds a BirthdayParty element that specifies a birthday party, consisting of a celebrant and a list of guests. The Q_OBJECT macro. If it finds one or more class declarations that contain the Q_OBJECT macro, it produces a C++ source file containing the meta-object code for those classes. There were just a couple things wrong, related specifically to QML: The context properties must be set before the engine loads the qml file. If this metatype represents an enumeration, this method returns a metatype of a numeric class of the same signedness and size as the enums underlying type. 6 answers. QML_IMPORT_MAJOR_VERSION = <version> to specify the import major version. Animations in QML are done by animating properties of objects. Hot Reload with Felgo Live allows you to change your QML & JavaScript source code and view the result in realtime. Use functor-based connect syntax if possilble. For licensing terms. When Qt 6 migrated to CMake, we also wanted to provide a nicer experience for setting up QML projects. The duration in millseconds of the media. . Add priority Enum in c++ for using in qml. int QMetaObject:: indexOfSignal (const char * signal) const. Qt's meta-object system provides the signals and slots mechanism for inter-object communication, run-time type information, and the dynamic property system. 11. Based on a simple C++ setting function per class (like Hibernate XML mapping file in Java), QxOrm library provides following features : . Both objects need to be of type typeId. In simplest terms (credit to this post): // header file of your choice namespace EquipmentNS { Q_NAMESPACE enum Ca. Syntax of an Import Statement. qml, to hold our UI definition in QML. This function registers the staticMetaObject and its extension in the QML system with the name qmlName in the library imported from uri having version number composed. But what about if we like to bind a QML property to a singleton object. class MyQmlType : public QObject. ) { qRegisterMetaType<EnumerationStorage::A> ("A"); qmlRegisterUncreatableMetaObject (EnumerationStorage::staticMetaObject,. qml to customize the width, height, radius and color properties of Button objects. // main. b 1. property attributes. Some have up to around 500 values. There are multiple ways to expose a C++ class to QML, each with their own benefits and quirks. This is the third installment in the series of blog posts on how to adjust your QML application to take the maximum advantage of qmlsc. Take a look at this article: Dynamic Object Management in QML and on this part especially: Note that. I think I have done everything right: The enum is in a separate class, derived from QObject The enum is registered. qml defines the attributes that are available to users of the Button component. [virtual protected] QVariant QQmlPropertyMap:: updateValue (const QString &key, const QVariant &input) Returns the new value to be stored for the key key. QQmlEngineExtensionPlugin is a plugin interface that lets you create QML extensions that can be loaded dynamically into QML applications. Registers a QML singleton object. When the Qml document is created there is no e. To make the custom type. More here. QML Type Compilation: that new Qt Quick Compiler part you have not heard much about. Add code to project until. Detailed Description The QtObject type is a non-visual element which contains only the objectName property. qml called images. ERROR: undefined reference to `Exception::staticMetaObject'. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. log(MyNamespace. The console. I tried to "mock" the C++ enum by such an QML enum just for the Designer, however, those enum's values are used like this QMLType. It defines and implements the language and engine infrastructure, and provides an API to enable application developers to extend the QML language with custom types and integrate QML code with JavaScript and C++. It works only in this case int qmlTypeId = qRegisterMetaType<namespace::MenuModel*> ("MenuModel*"); You return a pointer in the property, so Qt Meta Object system needs to know about it. target = qml DEPLOYMENTFOLDERS = folder_01 #Libraries QT. I use qmlRegisterType<_> ("a. qqmlengine. To print only dynamic property names, you can use the very aptly named dynamicPropertyNames () function of QObject from within an invokable C++ function: #include <QGuiApplication> #include <QtQml> class Object : public QObject { Q_OBJECT Q_PROPERTY (int staticProperty READ staticProperty) public: Object () { setProperty. If you're using qmake, create a qmldir file to describe the plugin. name> QML_IMPORT_MAJOR_VERSION = <version>. Qt + Smart LED Matrix + Raspberry Pi + IR Touch Bezel = FUN - glitchdraw/main. rootContext (). 1 MSVC 2019 x64 toolchain. Then instantiate your class object and expose it in main. Q_INVOKABLE bool startBackUp(SomeEnum i); The Enum is definied in *. h header: qmlRegisterType (), qmlRegisterSingletonType (), qmlRegisterUncreatableType () etc. QQmlPropertyMap provides a convenient way to expose domain data to the UI layer. 0. I defined an enum and a corresponding QFlags-specialization type inside a namespace marked with Q_NAMESPACE macro, also I registered this namespace's metaobject in QML system via qm. An object declaration in a QML document defines a new type. The Meta-Object Compiler, moc, is the program that handles Qt's C++ extensions. When QTransform::matrix property is set, it is decomposed to these transform components. Some have up to around 500 values. QML类型注册：QML类型注册用于在QML中申明一个在C++中定义的类型。让该类型或者数据可以在QML中进行访问。匿名类型：qmlRegister. But now I have a lot of enums created in this way. The Qt Meta-Object System in Qt is responsible for the signals and slots inter-object communication mechanism, runtime type information, and the Qt property system. It applies QML, JavaScript and asset changes instantly on every connected device, immediately after saving. The QMetaType class manages named types in the meta-object system. Persistence: support most common. This maintains their identity, and. int QQmlPropertyMap:: size const. Data Type Conversion Between QML and C++. 18. Now I want to get the class name from this object. } So far the simplest and cleanest solution I found is to make a C++ macro like this: #define QML_REGISTER (a) static int unused_val = qmlRegisterType<a> ("my_uri", 1, 0, #a) MyClass. There is the AUTOMOC_MACRO_NAMES target property you can set, but we should probably add Q_NAMESPACE to the default set. @ligabre this is because CMakes automoc does not recognize the Q_NAMESPACE keyword and therefore does not run moc on the header. Qt 5 - qmlRegisterType gives "module is not installed". 5 import QtQuick. It will catch more errors during compilation time. QFlags is used throughout Qt for storing combinations of enum values. TypeError: Cannot access enum value 'imgLoadAnim6' of 'AppEnumsNs', enum values need to start with an uppercase letter. For example, the following works: @. See Q_INVOKABLE. def connectSlotsByName (o). Member Function Documentation QQmlEngine:: QQmlEngine (QObject *parent = nullptr) Create a new QQmlEngine with the given parent. Qt uses a command line tool that parses these project files in order to generate "makefiles", files that are used by compilers to build an application. class PyQml (QObject): def __init__ (self, parent=None): super (). def checkConnectArgs (signal, method). I haven't tested this myself, but it should work:A tag already exists with the provided branch name. /***** ** ** Copyright (C) 2019 The Qt Company Ltd. PyQml. qmlRegisterUncreatableMetaObject(MyNamespace:: staticMetaObject, "io. index: qt-creator/qt-creator. property attributes. 0 import QtQuick 2. Until then you have to use qt5_wrap_cpp(moc_file ns. 0. EnumClasses. b",1,0,"c"); and import a. Business, Economics, and Finance. Yes, your suggestion helped in solving the issue. TEST_VIEW4 contains a QML folder with a specific folder for this QML code. The codec of the media's audio stream. hpp : #ifndef STYLE_HPP #define STYLE_HPP #include <QtGlobal> #if QT_VERSION < QT_VERSION_CHECK(5,0,0) // Qt 4 #include <QDeclarativeEngine> #else // Qt 5 #include <QQmlEngine> #endif // Required derivation from QObject class. See here to find out, how the names of variables and functions are resolved in QML. metaObject()->method(signalId). Hi, i will use this function from qml. It associates a type name to a type so that it can be created and destructed dynamically at run-time. I think the question is, are you using CMake or qmake? "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours". The QFlags<Enum> class is a template class, where Enum is an enum type. First, you define a class in Python, inheriting from QObject: class Console(QtCore. Creating a Client and. . Window 2. New Global Functions. Select Tools > Options > Environment > Keyboard. I've defined them all in the same way: namespace AppEnumsNs { Q_NAMESPACE typedef enum. py. Note that CMake will, by default, automatically generate the qmldir file. obj:-1: Error: LNK2001: unresolved external symbol "struct QMetaObject const Strings::staticMetaObject" (?staticMetaObject@Strings@@3UQMetaObject@@B) int qmlRegisterUncreatableMetaObject (const QMetaObject &staticMetaObject, const char *uri, int versionMajor, int versionMinor, const char *qmlName, const QString &reason) This function registers the staticMetaObject and its extension in the QML system with the name qmlName in the library imported from uri having version number composed from. hpp: #ifndef STYLE_HPP #define STYLE_HPP #include <QtGlobal> #if QT_VERSION < QT_VERSION_CHECK (5,0,0) // Qt 4 #include <QDeclarativeEngine> #else // Qt 5 #include <QQmlEngine> #endif //. QQmlApplicationEngine::QQmlApplicationEngine (const QString &filePath、 QObject *parent= nullptr) 新しい QQmlApplicationEngine を作成し、指定された場所に QML ファイルをロードします filePath、これはローカル ファイル パスである必要があります。. index: qt-creator/qt-creator. setContextProperty : Use setContextProperty, When you want to use a single global class to access to or from QML. In short, QT meta-object needs this to match the return type's name to your class' name: qRegisterMetaType<TObject> (); Share. The Slot does not exist yet at compile time. hpp header in every Rust module that needs it. . The Qt QML module provides a framework for developing applications and libraries with the . git. git. Select Tools > Options > Environment > Keyboard. [signal, since 5. An object declaration in a QML document defines a new type. 4) Click ‘ Install ’ to add the extension. It is not possible however to modify the global object, so true global JS-functions are not. If it finds one or more class declarations that contain the Q_OBJECT macro, it produces a C++ source file containing the meta-object code for those classes. The class is used as a helper to marshall types in QVariant and in queued signals and slots connections. I have registered an enum in a separate namespace using Q_ENUM_NS. QObject): @QtCore. You should read that post first in order to understand the others. The QML engine can instantiate any Qt C++ construct such as properties, functions, and data models into the QML context allowing the constructs to be accessible from within QML. Such an approach also makes changing the QML UI difficult without affecting its C++ counterpart. Those are some of the frequent steps I do follow to expose C++ classes to the QML engine. It was added in CMake 3. Deploy everywhere. The Meta-Object System. h header: qmlRegisterType (), qmlRegisterSingletonType (),. The selected items are stored using ranges. It also declares an object hierarchy that will be instantiated should an instance of that newly defined type be created. cpp then needs just this simple line outside of any function: EDIT: Sometimes this code makes the application to crash in debug mode. };. You can invoke it from the meta object.