Design pattern for GUI and NON GUI mode.

[jsulm]

@Ayush-Gupta To start the GUI application from your DLL you can use https://doc.qt.io/qt-5/qprocess.html
For loading the DLL and communicating with GUI app I already provided links before.

[Ayush Gupta]

I have tried launching my QT GUI application using QProcess in my DLL it works.
Also I have not created any instance of QApplication in my DLL hence no event loop is running in my DLL. I tried to communicate between DLL and QT GUI application by making QTcpServer in DLL and QTcpSocket in QT GUI application but I did not able to make communication successful may be because there is not event loop running in my DLL.

So I need to ask if we need to establish communication between QT DLL and QT GUI should I need to create instance of QApplication in DLL also to event loop get running?

[jsulm]

@Ayush-Gupta said in Design pattern for GUI and NON GUI mode.:

if we need to establish communication between QT DLL and QT GUI should I need to create instance of QApplication in DLL

Depends on what you use for communication. If you use Qt for that, then yes you need an event loop.

[Ayush Gupta]

I am using std::thread to invoke a QCoreApplication event loop. Here is my code
DLL.h

SharedLibrary *testShared;
std::thread *t;
void initDLL()
{

 testShared = new SharedLibrary;
        t = new std::thread(&SharedLibrary::init, testShared);
        testShared->startProcess();
        t->detach();
        testShared->startServer();

}

SharedLibrary.h

include <QObject>
#include <QThread>
#include <QCoreApplication>
#include <thread>
#include <QProcess>
#include "server.h"
class Q_DECL_EXPORT SharedLibrary :public QObject    
{
Q_OBJECT
public:
    SharedLibrary();
public:
    void init();
    void startProcess();
    void startServer();

private slots:

    //void onStarted();

private:

    QCoreApplication * app;
    Server *server_;
};

ShareLibrary.cpp

#include "SharedLibrary.h"
SharedLibrary::SharedLibrary()
{

}



void SharedLibrary::init()
{
    char * argv[] = {QString("dummy").toLocal8Bit().data(),NULL};
    int argc = sizeof(argv) / sizeof(char*) - 1;
    app = new QCoreApplication(argc, argv);
    app->exec();
}

void SharedLibrary::startProcess()
{
    QObject *parent = nullptr;
    QString program = "./TestPro.exe" ;
    QStringList arguments;
    arguments << "test";
    QProcess *myProcess = new QProcess(parent);
    myProcess->start(program,arguments);
    myProcess->write("test",4);
}

void SharedLibrary::startServer()
{
    server_ = new Server;
}

Still I am not able to send send data between Test application and DLL using Server and socket.
However if intialise the server in function init() it works .

It seems event loops exists in function init() only where the thread is created.

Is it not possible to make event loop global in class SharedLibrary?