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- markdown: |
    # Debugging with PDB

    - `pdb` is Python's built-in debugger
    - Available as a standard library
    - Easy to use
    - Powerful
    - https://docs.python.org/3/library/pdb.html

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- markdown: |
    ## A simple but broken script

    - Let us first study the script
    - Some useful programming principles


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- code: |
    %load data/broken.py

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    ## Debugging from IPython

    - Easy to get started

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- code: |
    %cd data

- code: |
    import broken

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    broken.test_simple()

- code: |
    %debug

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    ## `pdb` commands

    - `h(elp) [command]`
    - `p expression`
    - `s(tep)`
    - `n(ext)`
    - `q(uit)`
    - `l(ist) [first[, last]]`
    - `c(ontinue)`

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    ## More pdb commands

    - `w(here)`
    - `d(own) [count]`
    - `u(p) [count]`
    - `b(reak) [([filename:]lineno | function) [, condition]]`
    - `tbreak`
    - `pp expression`
    - `cl(ear) [filename:lineno | bpnumber [bpnumber ...]]`
    - `condition bpnumber [condition]`
    - `display [expression]`
    - `interact`
    - `run [args]`

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- code: |
    # Turn on auto-pdb
    %pdb

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- code: |
    %run -d script.py

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    %run -d -b20 script.py

- markdown: |
    ## Debugging from the console

    - Allows one to debug a script

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- code: |
    # Run this on a shell
    !python -m pdb broken.py


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    ## Adding a manual breakpoint in code

    Handy when writing code and you want to inspect at that point.

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    import pdb; pdb.set_trace()

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    ## More information

    - See  https://docs.python.org/3/library/pdb.html

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