So You Think You Can PDB?

This talk will be an introduction to the most commonly used Python Debugger commands and what they do. Learn how to navigate and inspect code from the pdb prompt so you can better understand how it works. The Python Debugger is a valuable debugging tool for all levels of Python programmers. You should walk away being able to debug the next Python code you encounter!

Transcript

1. So You Think You Can PDB? Clayton Parker So You Think You Can PDB? - Clayton Parker - PyCon 2015
2. Who am I? Director of Engineering at Six Feet Up claytron on the internets
3. What is PDB? Interactive debugging tool Pure awesome
4. How to invoke it? Set a trace directly in the code: import pdb; pdb.set_trace() Or start a script with pdb directly: $ python -m pdb example.py It is that easy!
5. Now what? Common commands Navigating the stack
6. Help Type help or ? for short to know what commands are available Further help on commands help help or help list
7. Show the current context Type list or l to see the current position in the code
8. Repeating the last command Just type return
9. Examine variables Type print or p to see what a variable is set to Use pp to pretty print the result for easier reading
10. Go to the next line Type next or n to go to the next line
11. Step into a function Type step or s to step into a function for further inspection
12. Skip over a loop Type until to skip over the end of a loop
13. Skip to the end of a function Type return or r to go to the end of a function
14. Breakpoints Type break or b to see a list of breakpoints Then b and a line number to set one To clear out a breakpoint clear or cl and a breakpoint number
15. Continue execution Type continue or c to go to the next breakpoint or finish execution
16. Conditional breakpoints Breakpoints can take an expression to know when to break: b 11, this_year == 2015
17. See where you are in the stack Type where or w to see the current stack You can debug at any point in the stack
18. Traverse the stack Type up or u to go up the stack Type down or d to go back down the stack
19. New features in Python 3: Interact Type interact to open an interpreter in the current scope
20. New features in Python 3: Long list Type longlist or ll to show the complete current function
21. All done Type quit or q to exit pdb and stop execution
22. PDB Alternatives PDB++ ipdb rpdb / remote-pdb
23. Helpers PdbSublimeTextSupport vimpdb flake8-debugger
24. .pdbrc Personalize your experience Set up aliases / custom mappings Enhance with readline support
25. Links Python Module of the Week: PDB In Depth PDB - Nathan Yergler