How do you debug without an interactive console

Question

As a self-taught programmer, I learned to debug using an interactive console that kept all of my variables in memory when I build /run the script. However, I noticed the overwhelming trend for debugging in IDEs (and, I suppose CLI + Editor solutions, for that matter) is to build your script in one place and provide a separate console "sandbox" type area that only keeps variables if you copy/paste your code.

How do you debug without an interactive console? Can anyone list a few debugging steps that could help me be a better programmer / debugger?

Currently, this is a very simplified version of what I do:

Write some pseudocode (sometimes)
Write some code in an editor that should work
run / build the script
Check stdout for errors
If no errors, then 7.
If errors, then back to 2 after fixing the offending code.
Type variable names into console to verify that they look like I anticipated.
Rinse and Repeat until it works as I intended.

@jh314 That answers a different question I had about how to run python scripts from within python. I now feel like a moron for not having heard of pdb, so your comment is extremely helpful. Thanks. — TheProletariat, Aug 05 '13 at 21:10

score 8 · Accepted Answer · edited May 23 '17 at 12:20

8

The best way to do this would be to write tests. That automates steps 3 through 7 for you. It also prevents regressions from occurring when you change other code.

edited May 23 '17 at 12:20

Community

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answered Aug 05 '13 at 20:30

Amber

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score 1 · Answer 2 · answered Aug 05 '13 at 20:30

you can use the q module for this easily https://pypi.python.org/pypi/q

xyxy.py

import q
do_something()
q.d() #this will open interactive shell

def f():
    do_something()
    q.d() #open console here with access to all local variables of f

you can also use automated tests (builtin unittest module or nosetests or something else)

score 1 · Answer 3 · answered Aug 05 '13 at 20:37

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Use a decent python IDE - there are a lot out there and you will be able to stop at breakpoints inspect variables by hovering or adding watches and enter a context console where you can interact with your code in the context of the breakpoint.

answered Aug 05 '13 at 20:37

Steve Barnes

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I actually got in StackOverflow trouble for asking the IDE question [here](http://stackoverflow.com/questions/18025529/is-there-a-python-ide-that-keeps-variables-in-memory?noredirect=1#comment26364918_18025529). Pycharm and many others do this like I am used to, but I'm picking up that it's not the *best* way to code. – TheProletariat Aug 05 '13 at 20:41
Which is best is a matter of opinion hence not a __good__ question - the _best_ way to code is to know it all and get it right first time. Doesn't happen that often to most of us. – Steve Barnes Aug 05 '13 at 20:49

score 1 · Answer 4 · answered May 30 '19 at 14:43

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Use print statements in between the areas of problem code... otherwise, just download a good IDE

answered May 30 '19 at 14:43

Emily Sheehan

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Increasingly, this is the answer I'm comfortable with. Thanks. – TheProletariat Jun 22 '19 at 04:31

score 0 · Answer 5 · answered Aug 07 '13 at 19:09

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It turns out that PyCharm, at least, DOES have an interactive console and the default keymapping (on Mac) is option-shift-E. Then your variables are loaded in memory. However, the suggestions above are better programming practices.

answered Aug 07 '13 at 19:09

TheProletariat

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How do you debug without an interactive console

5 Answers5