<![CDATA[Accessing mainwindow from another class]]>Hello guy's,

i have tried to include the mainwindow header to another class, lets call that class A, and from that class A then add a dock to the main window.

The problem is, that mainwindow already uses class A and has its header file included. So i get a circular dependency.

If i use forward declaration in class A and type "class MainWindow;" i can not really use any functions of the main window class in class A.

Is there someone with the same problem, or does someone have a solution on how to access the mainwindow class without a circular dependency?

Thanks a lot
Michael

]]>https://forum.qt.io/topic/134064/accessing-mainwindow-from-another-classRSS for NodeWed, 08 Apr 2026 21:49:10 GMTThu, 03 Feb 2022 18:47:47 GMT60<![CDATA[Reply to Accessing mainwindow from another class on Thu, 03 Feb 2022 19:13:07 GMT]]>Hi,

If you want to communicate with your main window, use signals and slots.

The fact that you start to have circular dependencies of that kind in a GUI application hints at an architectural issue.

]]>https://forum.qt.io/post/701277https://forum.qt.io/post/701277Thu, 03 Feb 2022 19:13:07 GMT<![CDATA[Reply to Accessing mainwindow from another class on Fri, 04 Feb 2022 14:32:35 GMT]]>@SGaist i did change a few things in the structure and now with signals and slots it works, thanks for the hint.

]]>https://forum.qt.io/post/701398https://forum.qt.io/post/701398Fri, 04 Feb 2022 14:32:35 GMT<![CDATA[Reply to Accessing mainwindow from another class on Thu, 03 Feb 2022 19:13:07 GMT]]>Hi,

If you want to communicate with your main window, use signals and slots.

The fact that you start to have circular dependencies of that kind in a GUI application hints at an architectural issue.

]]>https://forum.qt.io/post/701277https://forum.qt.io/post/701277Thu, 03 Feb 2022 19:13:07 GMT<![CDATA[Reply to Accessing mainwindow from another class on Thu, 03 Feb 2022 19:06:23 GMT]]>@JonB how can i then access the main window class?

I used something like MainWindow::addDockWidget(...) to add a dock to the main window.

If i don't include the header how can i access the mainwindow class?

]]>https://forum.qt.io/post/701276https://forum.qt.io/post/701276Thu, 03 Feb 2022 19:06:23 GMT<![CDATA[Reply to Accessing mainwindow from another class on Thu, 03 Feb 2022 18:49:23 GMT]]>@tiegert said in Accessing mainwindow from another class:

i have tried to include the mainwindow header to another class

Why? Don't. And then your issue will go away.

]]>https://forum.qt.io/post/701274https://forum.qt.io/post/701274Thu, 03 Feb 2022 18:49:23 GMT