The pdb Module

The pdb module is the standard Python debugger. It is based on the bdb debugger framework.

You can run the debugger from the command line (type n [or next] to go to the next line and help to get a list of available commands):

$ pdb.py hello.py > hello.py(0)?() (Pdb) n > hello.py() (Pdb) n hello again, and welcome to the show --Return-- > hello.py(1)?()->None (Pdb)

Example 11-2 shows how to start the debugger from inside a program.

Example 11-2. Using the pdb Module

File: pdb-example-1.py import pdb def test(n): j = 0 for i in range(n): j = j + i return n db = pdb.Pdb() db.runcall(test, 1) > pdb-example-1.py(3)test() -> def test(n): (Pdb) s > pdb-example-1.py(4)test() -> j = 0 (Pdb) s > pdb-example-1.py(5)test() -> for i in range(n): ...