In ruby the debugger is invoked by adding the statement

byebug

wherever you want to debug your code. This is preceded, of course, by a reference in Gemfile that brings in the byebug gem.

The python equivalent of this is two fold:

  • import the pdb (python debugger) gem
  • add the line pdb.set_trace() call where you want it

Here's the color coded example:

import pdb

# lines of python code here

pdb.set_trace()

That will launch the python debugger right before the line where the pdb.set_trace() call is inserted. Here are some useful commands:

  • The s key steps thru the code.
  • The n key goes to the next line.
  • The q key quits.

More on Python Debugging.