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Debugging with pdb.set_trace() Nicole Zuckerman Clover Health @zuckerpunch

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What is PDB?

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From the docs: Or:

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What is this set_trace() that you’re doing a whole talk about?

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set_trace(), in action

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But I already have print statements. What more do I need?

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What’s so great about set_trace()? 1. Inspect contents of variables during real-time execution 2. Traverse call frames 3. Travel through execution order 4. Change live code during execution

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Code sample time

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Inspect contents of variables during execution

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Inspect contents of variables during execution Inspecting arguments of currently paused function:

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Inspect Variables continued: print/pretty print

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Inspect Variables continued: print/pretty print

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Inspect Variables continued: print/pretty print

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Inspect Variables continued: print/pretty print

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Traverse frames in call stack

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Traverse Call Frames

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Traverse Call Frames

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Traverse Call Frames

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Traverse Call Frames

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Traverse Call Frames

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Travel through execution

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Traveling through execution

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Traveling through execution

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Traveling through execution

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Where the heck am I, anyway?

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No content

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List: The Fancy Parts

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Change live code during execution

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Changing live code during execution

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PDB-adjacent coolness: my_thing.__dict__

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PDB-adjacent coolness: dir(my_thing)

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PDB-adjacent coolness: dir(my_thing)

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Pdb gotchas

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Gotchas pdb commands versus statements

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Gotchas

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Gotchas The Enter key

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Bonus! Post-mortem debugging

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Code sample with exception-inducing bug

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Post-mortem at work

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Breakpoints

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Break!

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Break!

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Clear!

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No content

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https://docs.python.org/2/library/pdb.html Questions