Is QPluginLoader::instance() calling the plugin's constructor?

[Petross404_Petros S]

Hi,

I want to experiment with an abstract IFace that will be inherited by PluginA and PluginB.

Now, I know I am supposed to cast like this and test for nullptr:

if( auto d = qobject_cast<IFace*>(loader->instance(); d != nullptr)
{
    d->doSomething();
}

But how my plugin's ctor was called and the object allocated memory?

I can register the plugins and provide an IFace* IFace::create() interface to call the ctor and use with the factory pattern.

Is this the way to initialize (test loader->instance and use the factory pattern) the correct way?

Thank you.

[SGaist]

Hi,

If I understand your intents correctly, your plugin shall provide the factory method as interface and then you can build your objects with your actual inherited interface.

[Petross404_Petros S]

Hi,

At the moment I have a DriverFactory with registerPlugin(const QString& driverName, callback_t cb), IDriver* createDriver(QObject* parent) etc. This class keeps it's data in a std::map<QString, callback_t>.

My plugins have a static function like static IDriver* createInstance(QObject* parent);

But it seems QLibrary needs to resolve extern "C" functions who can't be static. Anyway, I will mark this as solved since the topic is no longer relevant.

[Christian Ehrlicher]

@Petross404_Petros-S said in Is QPluginLoader::instance() calling the plugin's constructor?:

who can't be static

This would somehow contradict the 'static' keyword - a static function is only visible in the translation unit where it was defined.