Add to Qt GUI logger functionality

[Christian Ehrlicher]

@Gaetano03 said in Add to Qt GUI logger functionality:

I have it declared in my logger_widget.h class file (if you also see my previous reply), but was thinking maybe should be declared outside of the class?

You should also instantiate it somewhere.

[Gaetano03]

@Christian-Ehrlicher

I have it declared and instantiated both in the logger_widget.h class among the private members

private:
    Ui::logger_widget *ui;

    integer::logger::errors err_init;
    integer::logger::integer_logger& logger = integer::logger::integer_logger::get_instance();
    integer_interface *myApp = qobject_cast<integer_interface *>(qApp);

and in the static log function

void log(std::string message)
{
    integer_interface *myApp = qobject_cast<integer_interface *>(qApp);
    emit myApp->libraryLogged(message);
}

as suggested by @JonB

PS
@JonB doing as you suggested as sanity check with the following lines

    integer_interface *myApp = qobject_cast<integer_interface *>(qApp);
    Q_ASSERT(myApp);

gives a bunch of errors not sure I understand:
logger_widget.h:42:14: C++ requires a type specifier for all declarations

logger_widget.h:42:5: Expected ')'
0:0: :42:5: note: to match this '('

logger_widget.h:42:14: Duplicate member 'myApp'
logger_widget.h:41:24: previous declaration is here

[JonB]

@Gaetano03
Look, can you please show your main() function now. I have a funny feeling your still have QApplication a(argc, argv); there, and what do you think you actually need instead of that?

[JonB]

@Gaetano03 said in Add to Qt GUI logger functionality:

integer_interface *myApp = qobject_cast<integer_interface *>(qApp);
Q_ASSERT(myApp);

If that is in a .h where you are declaring member variables in a class definition you cannot add arbitrary C++ statements to execute..... Put the qobject_cast<> in the constructor, where you can verify it.

[Gaetano03]

@JonB
you have the right funny feeling, just realized how silly I was.

Everything works fine now and I get stuff printed on my QPlainText, at least for now XD.

Thanks a lot, really!

I really appreciate

[JonB]

@Gaetano03
Yeah, do you get the point? You can subclass QApplication to add whatever you want, but then you must create a SubclassedApplication not the original base class QApplication to use it. Just like any other subclassing.

qApp() macro returns QApplication *-type pointer, for whatever (single) QApplication instance has been created. If you derived and created the derived instance, qApp won't return that derived type (though it will return the correct derived instance). So to call methods/access variables you defined in your subclass that's why we qobject_cast<SubclassedApplication *>(qApp).

[Gaetano03]

@JonB
Yes I got the point, thanks also for this explanation!! That helps a lot understanding what I am doing behind the lines!!!

I have to admit that I worked so much on the library that I forgot for a while a main calling it and launching the app was even existing XD