Debug leftovers: debugger, breakpoint(), print("here"), print(f"{x=}"), dbg!

Code nobody needs: one of the ways AI coding agents bloat software, from lessloc's pattern catalog. lessloc catches it as debug-leftover.

What makes debug leftovers a bad practice?

The standards that call it a bad practice: CWE-489 Active Debug Code; ESLint no-debugger; Sonar S4507; clippy dbg_macro.

What does lessloc do about debug leftovers?

lessloc catches it as debug-leftover. It is judged at turn end, because mid-work the print may still be in use.

• debug-leftover (tier 1): debugger, breakpoint(), pdb.set_trace(), or a debug print such as print("here"). Judged when the turn ends.

Examples

Caught as debug-leftover:

export function total(xs) {
  debugger;
  console.log("here");
  return xs.length;
}

Written well:

export function total(xs) {
  console.log(`total of ${xs.length} items`);
  return xs.length;
}

Caught as debug-leftover:

def total(xs):
    breakpoint()
    print(f"{xs=}")
    return len(xs)

Written well:

def total(xs):
    print(f"{len(xs)} items")
    return len(xs)

Related patterns

The other patterns in Code nobody needs:

• Options, flags, parameters or config for needs nobody named: lessloc gives every session a rule against it and catches it as mode-flag.
• An interface or abstract class with one implementation: lessloc catches it as single-impl.
• Wrappers that only forward; barrel files that only re-export: lessloc catches it as wrapper.
• A new function or import that nothing calls or tests: lessloc catches it as unused (ruff adds unused variables).
• Obsolete code kept behind a guard or flag instead of deleted: lessloc gives every session the rule: delete what the change makes dead.
• Tombstones: lessloc catches it as history.
• Stubs and fake success: lessloc catches it as stub; it asks to finish the code or to tell the user what is not real yet.
• Placeholders: # ... existing code ..., "your code here": lessloc catches it as placeholder and refuses it before it lands.
• Commented-out code: lessloc catches it as commented-out and refuses it before it lands.
• A demo __main__ block or demo folder nobody asked for: lessloc catches it as demo-code and new-folder.
• Hand-written boilerplate a language feature writes: lessloc catches it as simpler.
• A one-line helper used once: lessloc catches it as single-use.
• TODO and FIXME left behind: lessloc catches it as todo; it asks to finish the work, or to record known debt as shortcut: and tell the user.