2017 - Peter Hadlaw - Intro to pdb

Transcript

1. INTRO TO pdb Peter Hadlaw @ Tesorio August 13, 2017

   https://www.tesorio.com/careers

2. TOO OFTEN I SEE... print foo print foo['bar'] print fizz.buzz()

   ...

3. CONS: Limited (can't interrupt execution) Messy (lot's of clean up)

   Zero interactivity (need to modify code and run everything again) Much harder to dive deeper into third party code (internal or external alike)

4. DEBUGGER Exist in many languages and platforms Python's built-in debugger

   is... "A computer program that assists in the detection and correction of errors in computer programs."

5. pdb

6. THREE EASY STEPS 1. Set a breakpoint 2. Run program

   3. Execution halts at breakpoint and now, you, interact

7. SETTING A BREAKPOINT import pdb; pdb.set_trace() Using a one liner

   is a nice habit to make clean up easier (e.g. a single dd in vi).

8. api.py

9. RUN PROGRAM

10. l - LIST COMMAND

11. EXPRESSIONS

12. n - NEXT COMMAND

13. s - STEP COMMAND

14. c - CONTINUE COMMAND

15. GENERAL FLOW Use l to orient yourself and inspect what

    code is currently being executed. Use n to step forward in execution Use s to dive deeper Create expressions for the debugger to evaluate and gain insights into what's happening c to continue execution until next breakpoint / finish Profit.

16. NOTES More commands and features available iPython version, much more

    powerful (has to be installed separately) Other languages have debuggers to, for example JavaScript in the browser, or C (gdb)

17. WE'RE HIRING https://www.tesorio.com/careers