Modify value in child qwt plot

[titipoof]

Dear Qt users & experts,
I am a noob at Qt, but since it can do nice things it catched my interest, I will try to explain my problem in short :
I enbedded two qwtplot inside two different groupbox in a mainwindow. In this main window I have a table (made from QabstractItemModel but I can change it). The idea is to click on the graph to get the value where u click. I managed to show this value in a messagebox. Everything worked nicely, except that I have problem for transferring the value to the main window.

I tried to inherit Plot from MainWindow, but it is normally like : "class Plot : public QwtPlot ....."
But it seems double inheritance is not good when using connect in further step...

I have seen also that it seems possible to declare global variables, but I have seen also that it is not recommended, not really in object-oriented programmation spirit.

I don't know what is the best approach to this problem, can u help me?

[titipoof]

I found a simple way :

In mainwindow.cpp :
QString texto="blabla"; // initialisation

In plot.cpp :
extern QString texto; // taking extern variable


Do you think it is a nice way of doing it? Can I use the header maybe?
I was recently programming in perl and fortran, so I guess I can make things working but I would want to write things in a not dirty way
It is basically solved, but I would want ur advices to write better code

[bigjoeystud]

The Qt way of doing this is with their signal/slots mechanism. Basically, you emit/throw a signal when an event happens and you use a slot to catch the event in your main window. If you write the event handler of your Plot to emit this signal, the main window just needs to connect to it.

Hope that helps!
Joey