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gh-154675: Use lazy imports in pdb, bdb, code #156567

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gh-154675: Use lazy imports in pdb, bdb, code #156567

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8 changes: 4 additions & 4 deletions Lib/bdb.py
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Original file line number Diff line number Diff line change
@@ -1,12 +1,12 @@
"""Debugger basics"""

import fnmatch
import sys
import threading
import os
import weakref
import sys
from contextlib import contextmanager
from inspect import CO_GENERATOR, CO_COROUTINE, CO_ASYNC_GENERATOR
lazy import fnmatch
lazy import threading
lazy import weakref

__all__ = ["BdbQuit", "Bdb", "Breakpoint"]

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2 changes: 1 addition & 1 deletion Lib/code.py
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Original file line number Diff line number Diff line change
Expand Up @@ -7,8 +7,8 @@

import builtins
import sys
import traceback
from codeop import CommandCompiler, compile_command
lazy import traceback

__all__ = ["InteractiveInterpreter", "InteractiveConsole", "interact",
"compile_command"]
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54 changes: 26 additions & 28 deletions Lib/pdb.py
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Original file line number Diff line number Diff line change
Expand Up @@ -67,45 +67,44 @@

import os
import io
import re
import sys
import cmd
import bdb
import dis
import bdb
import code
import glob
import json
import stat
import token
import types
import atexit
import codeop
import pprint
import signal
import socket
import typing
import asyncio
import inspect
import weakref
import builtins
import tempfile
import textwrap
import tokenize
import itertools
import traceback
import linecache
import selectors
import threading
import _colorize

from contextlib import ExitStack, closing, contextmanager
from types import CodeType
from warnings import deprecated

try:
import _pyrepl.utils
except ModuleNotFoundError:
_pyrepl = None
lazy import _colorize

@StanFromIreland StanFromIreland Aug 29, 2026

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Hmm, this is now different to the other files, where we have lazy imports directly after the regular imports.

@hugovk hugovk Aug 29, 2026

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The isort/ruff rule is:

import a
from b import c
lazy import d
lazy from e import f

And this is following that, except I left the spaces between groups, but can remove those if you like?

lazy import argparse
lazy import asyncio
lazy import glob
lazy import json
lazy import pprint
lazy import re
lazy import runpy
lazy import selectors
lazy import shlex
lazy import signal
lazy import socket
lazy import tempfile
lazy import textwrap
lazy import threading
lazy import tokenize
lazy import traceback
lazy import weakref


class Restart(Exception):
Expand Down Expand Up @@ -246,7 +245,6 @@ class _ModuleTarget(_ExecutableTarget):
def __init__(self, target):
self._target = target

import runpy
try:
_, self._spec, self._code = runpy._get_module_details(self._target)
except ImportError as e:
Expand Down Expand Up @@ -281,8 +279,6 @@ def namespace(self):

class _ZipTarget(_ExecutableTarget):
def __init__(self, target):
import runpy

self._target = os.path.realpath(target)
sys.path.insert(0, self._target)
try:
Expand Down Expand Up @@ -465,6 +461,7 @@ def complete(self, text, state):
return None

def gen_colors(self, buffer):
import _pyrepl.utils
from _pyrepl.utils import ColorSpan, Span

if not buffer.strip():
Expand Down Expand Up @@ -1266,7 +1263,11 @@ def handle_command_def(self, line):
return False

def _colorize_code(self, code):
if self.colorize and _pyrepl:
if self.colorize:
try:
import _pyrepl.utils
except ModuleNotFoundError:
return code
colors = list(_pyrepl.utils.gen_colors(code))
chars, _ = _pyrepl.utils.disp_str(code, colors=colors, force_color=True)
code = "".join(chars)
Expand Down Expand Up @@ -2084,7 +2085,6 @@ def do_run(self, arg):
'e.g. "python -m pdb myscript.py"')
return
if arg:
import shlex
argv0 = sys.argv[0:1]
try:
sys.argv = shlex.split(arg)
Expand Down Expand Up @@ -3778,9 +3778,7 @@ def parse_args():
# "python -m pdb -m foo -p 1" should pass "-p 1" to "foo".
# "python -m pdb foo.py -m bar" should pass "-m bar" to "foo.py".
# "python -m pdb -m foo -m bar" should pass "-m bar" to "foo".
# This require some customized parsing logic to find the actual debug target.

import argparse
# This requires some customized parsing logic to find the actual debug target.

parser = argparse.ArgumentParser(
usage="%(prog)s [-h] [-c command] (-m module | -p pid | pyfile) [args ...]",
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5 changes: 5 additions & 0 deletions Lib/test/test_bdb.py
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,7 @@
import linecache
from contextlib import contextmanager
from itertools import islice, repeat
from test.support import cpython_only
from test.support import import_helper
from test.support import os_helper
from test.support import patch_list
Expand Down Expand Up @@ -1232,6 +1233,10 @@ def test_next_to_botframe(self):


class TestRegressions(unittest.TestCase):
@cpython_only
def test_lazy_import(self):
import_helper.ensure_lazy_imports("bdb", {"fnmatch", "threading", "weakref"})

def test_format_stack_entry_no_lineno(self):
# See gh-101517
self.assertIn('Warning: lineno is None',
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5 changes: 5 additions & 0 deletions Lib/test/test_code_module.py
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@
from textwrap import dedent
from contextlib import ExitStack
from unittest import mock
from test.support import cpython_only
from test.support import force_not_colorized_test_class
from test.support import import_helper

Expand Down Expand Up @@ -38,6 +39,10 @@ def setUp(self):
self.console = code.InteractiveConsole()
self.mock_sys()

@cpython_only
def test_lazy_import(self):
import_helper.ensure_lazy_imports("code", {"traceback"})

def test_ps1(self):
self.infunc.side_effect = [
"import code",
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28 changes: 27 additions & 1 deletion Lib/test/test_pdb.py
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Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,7 @@
from io import StringIO
from test import support
from test.support import has_socket_support, os_helper
from test.support.import_helper import import_module
from test.support.import_helper import ensure_lazy_imports, import_module
from test.support.pty_helper import run_pty, FakeInput
from test.support.script_helper import kill_python
from unittest.mock import patch
Expand Down Expand Up @@ -3529,6 +3529,32 @@ class PdbTestCase(unittest.TestCase):
def tearDown(self):
os_helper.unlink(os_helper.TESTFN)

@support.cpython_only
def test_lazy_import(self):
ensure_lazy_imports(
"pdb",
{
"_colorize",
"argparse",
"asyncio",
"glob",
"json",
"pprint",
"re",
"runpy",
"selectors",
"shlex",
"signal",
"socket",
"tempfile",
"textwrap",
"threading",
"tokenize",
"traceback",
"weakref",
},
)

@unittest.skipIf(sys.flags.safe_path,
'PYTHONSAFEPATH changes default sys.path')
def _run_pdb(self, pdb_args, commands,
Expand Down
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2026-08-29-13-41-56.gh-issue-154675.cYvE-Z.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Improve import time of :mod:`pdb`, :mod:`bdb` and :mod:`code` by lazily
importing several dependencies.
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