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Accessing application classes from a plugin?

  • I create a plugin that implements my application's plugin interface, as in the Echo Plugin Example.

    Now, how can I access classes (other than the plugin interface) that are declared and defined in the application? When I try to instantiate one of the application classes in the Plugin, I get an unresolved external symbol linker error, which is expected.

    Is there a way to do this without building a library out of my application that contains those classes, and then linking it dynamically in both the application and the plugin?

  • Maybe you can add a CLASSNAME POINTER* into your Plugin-Interface (do not forget to add foreward declaration of the class => class CLASSNAME) and do somethink like that when you init your plugin:

    QPluginLoader loader(fileName);
    QObject *possiblePlugin = loader.instance();
    if (possiblePlugin)
        PluginInterface *plugin = qobject_cast<PluginInterface*>(possiblePlugin);
        if (plugin)
            qInfo() << "Loaded plugin: " << plugin->get(NAME);
            plugin->core = this->m_core;

    Now you can work and have access inside your plugin with the CLASSNAME you want. In my example "core". Be carefull maybe it should be const.

    Inside Plugin: core->whatEVER();

  • Lifetime Qt Champion


    Move all the classes that you want to be able to use in both your application and plugin in a shared library and link your plugins as well as your application against said library.

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