Load library and calling functions of main app

[Eugene]

Hello! Sorry for poor language.

I load library, give him pointer to main app and after that call main app public functions from library . But I get error message.
"symbol lookup error: /home/jeka/QtPro/MyPlugin/plug/libMy_plug.so: undefined symbol: _ZN10MainWindow8set_textEv"
What I should to do to call main app publick functions from my plugin?
If it's hard what I should to learn?

[Jeroentjehome]

Well, without code, no way of telling what you are doing now, or what is the real solution. But loading a QLibrary also needs to "resolve" function pointers to the functions in the library. The symbol lookup error gives an indication that QLibrary couldn't find the requested function. When using a C-API library it should always work. If you use a C++ library you need to use the same compiler for the library and your Qt project, this to do with name mangling.

[SGaist]

Hi and welcome to devnet,

Since you are using Qt I assume that you have a QApplication, then you don't need to pass the pointer to your QApplication instance around. Just use the qApp macro in your code.

Your error seems related to a MainWindow class, are you sure that this class is known to your plugin ?

[Eugene]

Thanks for answers. My code is ugly))
I write some functions prototype, if it isn't enough. Please tell me how to share my project?
@
// mainwindow.cpp
#include "iface.h" // interface class
void MainWindow::load_plugins()
{
//... other code.
QPluginLoader loader(dir.absoluteFilePath(strFileName));
// iface plugin; private member
plugin = qobject_cast<iface>(loader.instance());
plugin->set_main_app_pointer(this) ;
//...
}
void MainWindow::on_pushButton_clicked()
{
plugin->call_mainwindow_function();
}
void MyPlugin::call_mainwindow_function()
{
//MainWindow *window - my plugin's private member
qDebug() << window->metaObject()->className(); // give "MainWindow" string
window->set_label_text(); //Error
}

void MainWindow::set_label_text() // main app public function
{
ui->label->setText("Hello!!!");
}
@

[dbzhang800]

Hi,
It's really not a good idea to let your plugin depend on your application.

You need to define a Interface class, then use it in both your application and your shared library.