Debugging skills are key to making your programs work properly. Here I show you how to step through our previous numbers.py in PyDev's graphical debugger, watching how the variables are created and changed, seeing how the stack changes and using breakpoints for control.
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When debugging we need PyDev's debug-perspective, we launch using F11 and then Step Into and Over lines of code and watch how things evolve on the stack and variable list (hint: their colour changes). At the end of the video I show you how to switch back to the normal editing perspective from the debug perspective.
By the end of the video you'll be comfortable with PyDev's debugger and you will be able to step into and around your own code. This will give you more power in understanding how your program is running and what's going on 'under the hood'.
I mention the Change Value/Set Value menu option in the video (when debugging, in the Variables tab) - I have confirmed with Fabio (the author) that this feature is not implemented in the current version of PyDev (let Fabio know that you saw it here and ask for it to be supported!)
For more on debugging with Python (using the stock pdb, not PyDev) see Interactive Debugging in Python by Jeremy Jones. Now come join me in the forum for questions and tasks.