Python has a debugger called pdb. Let's find out how can we use it instead of Pycharm.

To The Point

Calling PDB Stack Trace

There is a PDB class that enables python debugging without additional python packages.

To use it, call stack-trace like that:

import pdb


The line in which you will put pdb.set_trace() is the one from which pdb will invoke stack-trace.

There is also a way in which you will start function without setting particular line at which stack-trace should start:

import pdb
import yourmodulename'yourmodulename.yourfunction()')

Using PDB - commands to move in pdb stack-trace

PDB stack trace is interactive - in a similar way as in Pycharm.

You can use commands in pdb to analyze stack-trace.

You can either write one letter of the command or full name of command - but some of the commands needs to be written in a full-length.

The most used commands:

  • u(p) - moves current stack-trace frame up
  • d(own) - moves current stack-trace frame down
  • b(reak) [([filename:]lineno | function) [, condition]]
    • without argument lists all set-up breaks.
    • first argument sets up breakpoint at specific filename/function and line number.
    • second argument gives option to break only on specific python condition
  • cl(ear) [filename:lineno | bpnumber [bpnumber ...]]
    • without argument clears list of all set-up breaks.
    • with first or second argument, gives option to distinct which breakpoints needs to be cleared.
  • s(tep) - executes current line
  • n(ext) - moves to next line of funtion or returns if not found.
  • r(eturn) - continue execution until current function returns.
  • q(uit) - quit from debugger.

The full documentation about commands can be found at the pdb documentation page on python docs


import pdb; pdb.set_trace()



Related links


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See you in the next episode! Cheers!


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