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Qml call c++ function with CMake



  • If i use qmake, the following way works fine: If i want call a function from the class Test2, i do the following:
    test2.h:

    #ifndef TEST2_H
    #define TEST2_H
    
    #include <QObject>
    
    class Test2: public QObject
    {
        Q_OBJECT
    public:
        Test2();
    public slots:
        int testit();
    };
    
    #endif // TEST2_H
    

    test2.cpp:

    Test2::Test2()
    {
    
    }
    
    int Test2::testit()
    {
        return 6;
    }
    

    main.cpp:

    #include <QGuiApplication>
    #include <QQmlApplicationEngine>
    #include <QQmlContext>
    #include "test2.h"
    
    int main(int argc, char *argv[])
    {
        QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
    
        QGuiApplication app(argc, argv);
    
        QQmlApplicationEngine engine;
    
        QQmlContext* context= engine.rootContext();
        Test2 test2instance;
        context->setContextProperty("test", &test2instance);
    
    
        engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
        if (engine.rootObjects().isEmpty())
            return -1;
    
        return app.exec();
    }
    
    

    CMakeList:

    cmake_minimum_required(VERSION 3.1)
    
    project(QMLCmake LANGUAGES CXX)
    
    set(CMAKE_INCLUDE_CURRENT_DIR ON)
    set(CMAKE_AUTOMOC ON)
    set(CMAKE_AUTORCC ON)
    set(CMAKE_CXX_STANDARD 11)
    set(CMAKE_CXX_STANDARD_REQUIRED ON)
    
    find_package(Qt5 COMPONENTS Core Quick REQUIRED)
    
    add_executable(${PROJECT_NAME} "main.cpp" "qml.qrc")
    target_compile_definitions(${PROJECT_NAME} PRIVATE $<$<OR:$<CONFIG:Debug>,$<CONFIG:RelWithDebInfo>>:QT_QML_DEBUG>)
    target_link_libraries(${PROJECT_NAME} PRIVATE Qt5::Core Qt5::Quick)
    
    

    So i can call test.testit() in qml. But if i do this with CMake it doesn't work. The error message is: error: undefined reference to `Test2::Test2()'.


  • Lifetime Qt Champion

    When you don't add test2.cpp to the sources to compile the linker also cant find the class...



  • If i have a normal c++ project, i didn't add the source file, too.
    But if i add

    set( project_sources
       main.cpp
       test2.cpp
    )
    

    it doesn't work, either.



  • Thank you very much. I don't added the source file to executable. Now all works fine.


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