This is a Today I Learned, meaning this is for me, written in my voice the way I want.
I wouldn’t say I’m new to debuggers since I’ve used them in various IDEs over the years for several languages. What I am new to is using the barebone version of them straight from the terminal.
I’m on the journey of migrating to Vim and learning a new way to operate. I’ve started looking into nvim-dap plus dap-ui but the default options are difficult to configure, an information overload, and hard to have run consistently across projects. Which lead me to PDB and this crash course by assotile.
Other tools claim to be easy, PDB is truly easy. Simple to configure, move around, and explore.
How to install pdb?
Fortunately PDB comes baked into modern Python versions (3.7+). You now just have to set breakpoints in your code.
Ways to set breakpoints The classic way to set a breakpoint is to import pdb then call set trace method like so:
import pdb
pdb.set_trace()
In Python 3.7+ they’ve added a convenience method:
breakpoint()
Once set you’re ready to run with a debugger.
Run your python as normal. You should the pdb repl:
> /Users/rodrigomoran/Workspace/scratch/using_pdb/main.py(6)main()
-> for user in users:
(Pdb)
Showing help
help
(Pdb) help
Documented commands (type help <topic>):
========================================
EOF c d h list q rv undisplay
a cl debug help ll quit s unt
alias clear disable ignore longlist r source until
args commands display interact n restart step up
b condition down j next return tbreak w
break cont enable jump p retval u whatis
bt continue exit l pp run unalias where
Miscellaneous help topics:
==========================
exec pdb
(Pdb) h c
Usage: c(ont(inue))
Continue execution, only stop when a breakpoint is encountered.
(Pdb)
Quiting
(Pdb) q
Continue til next breakpoint
(Pdb) c
Step into function
(Pdb) s
Step out