Python 3 reference · Built-in Functions

Python breakpoint() Function

Pause the program and open the debugger at this line. It calls sys.breakpointhook(), which starts pdb by default.

Syntax

breakpoint(*args, **kws)

Parameters

Parameter	Description
`args, *kws` optional	Passed on to `sys.breakpointhook()`.

Return value

Whatever the hook returns (usually None).

Examples

What happens when breakpoint() runsTry it yourself

import sys

# Replace the hook so this example doesn't wait for debugger input
sys.breakpointhook = lambda *args, **kws: print("debugger would open here")

total = 0
for n in [3, 5]:
    total += n
    breakpoint()
print("total:", total)

sys.breakpointhook = sys.__breakpointhook__  # restore the default

Output

debugger would open here
debugger would open here
total: 8

Configure or disable itTry it yourself

import os, sys

# The PYTHONBREAKPOINT environment variable controls the hook:
#   PYTHONBREAKPOINT=0                 -> breakpoint() does nothing
#   PYTHONBREAKPOINT=module.function   -> call that function instead of pdb
print(sys.__breakpointhook__.__name__)  # the default hook
print(os.environ.get("PYTHONBREAKPOINT", "not set"))