I would like to see the coding that is executed when working in QGIS e.g. using the tool bars and performing tasks in the GUI. Is there a way to see what coding is going on behind the GUI?

I would like to slightly edit what some of the functions do and need to see the code executed when I use the functions.

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    In terms of using functions from the Processing Toobox, you can check the history log to see how they are executed in code (from the toolbar Processing > History). – Joseph Feb 26 '18 at 10:15

QGIS is open source, so you can always see what its doing. The source code is here:


if you follow the instructions to build QGIS from source then you can run it with a debugger and step through the code, or add extra logging to see what is going on. You will need some knowledge of C++ and build systems (QGIS uses cmake) and you'll have to install a few dependencies to get it working.

You might be able to get what you want just by inspecting the code at github without having to compile it.


I'm not an expert in that field but the use of listeners in python is also a way to check whether and when given events are triggered.That gives you the possibility to execute your own code or to log things ... that's a way to check how QGIS exactly behaves.

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