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Comment by stuntcoder | Hacker News Reader

I promise the 15 minutes it takes to learn to use the debugger will save years of your life

Not necessarily. I know very well how to use a debugger, but nowadays I just prefer to use prints: it forces to you actually think about what's happening instead of just looking at it. It's also more useful in situations where putting a debugger actually changes behavior (high performance systems, parallel programs).

Exactly. And prints are cross platform cross language etc.

I would expect print-debugging to change the behavior in such cases too. Usually writing to stdout is behind some synchronization so using print debugging will drop performance and make program less parallel.

You can change where to put the prints if they do change the behavior (which incidentally also helps in understanding what's happening). You can print only if a condition happens, or only before/after critical sections, or print counters that you compute in the fast path. With the debugger you're always taking the overhead in and breakpoints will always change the flow of the program.

The issue is that the debugger stops execution at the breakpoint, but most often I want to analyze multiple print statements together. The debugger and repl have their uses, but IMHO I am usually better served by adding a print and having the script automatically re-run itself.

Which debugger would you recommend?

For Python: ipdb. In your code, you can just drop in "import ipdb; ipdb.set_trace()" and the execution will stop there with an interactive prompt. Alternatively start the script through (i)pdb and set breakpoints.

You can also use plain pdb ("import pdb; pdb.set_trace()"), which has the advantage that it comes with the Python stdlib, but the interactive prompt is less fancy (no history, no autocompletion, etc).

Add `export PYTHONBREAKPOINT=ipdb.set_trace` to your .bashrc and "breakpoint()" will invoke ipdb by default.

That is a great trick, thank you!

i use this frequently! but print() is still handy and my go to

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