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gh-109653: Improve import preformance of tkinter library with lazy imports #148409

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gh-109653: Improve import preformance of tkinter library with lazy imports #148409

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f0e2f9b
Lazy import modules in tkinter __init__
sharktide Apr 11, 2026
4bcb491
Add _get_magic_re and _get_space_re functions.
sharktide Apr 11, 2026
995d6a1
Update usage in _stringify
sharktide Apr 11, 2026
44567a4
Add docstring to new functions
sharktide Apr 11, 2026
0dfab78
Format
sharktide Apr 11, 2026
ce94f9e
Add NEWS entry
sharktide Apr 11, 2026
01000ea
Move lazy import re down in the file
sharktide Apr 12, 2026
1da6e7b
Reorder imports for clarity
sharktide Apr 12, 2026
f0bd1eb
Stop lazy imported modules from appearing in __all__
sharktide Apr 12, 2026
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39 changes: 25 additions & 14 deletions Lib/tkinter/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -29,16 +29,15 @@
button.pack(side=BOTTOM)
tk.mainloop()
"""

import _tkinter # If this fails your Python may not be configured for Tk
from tkinter.constants import *
import collections
import enum
import sys
import types

import _tkinter # If this fails your Python may not be configured for Tk
lazy import sys
lazy import types
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@danielhollas danielhollas Apr 12, 2026

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Looking at the code, I think both sys and types will end up being imported always, because of:

https://github.com/python/cpython/pull/148409/changes#diff-46c8ee2e6d4e02b7a2839d0cabde53331f5ad74fb09fdd6149b70e9d5cfb2cddR5107
https://github.com/sharktide/cpython/blob/f0bd1ebd7c4c6ac7126d7fc8332e59744427d6fc/Lib/tkinter/__init__.py#L2635

At the same time, there are some inline imports that you can convert to lazy syntax: traceback and os
https://github.com/sharktide/cpython/blob/f0bd1ebd7c4c6ac7126d7fc8332e59744427d6fc/Lib/tkinter/__init__.py#L2622
https://github.com/sharktide/cpython/blob/f0bd1ebd7c4c6ac7126d7fc8332e59744427d6fc/Lib/tkinter/__init__.py#L2539

(though you should checj again whether os will end up being imported anyways)

lazy import re
TclError = _tkinter.TclError
from tkinter.constants import *
import re

wantobjects = 1
_debug = False # set to True to print executed Tcl/Tk commands
Expand All @@ -50,22 +49,33 @@
WRITABLE = _tkinter.WRITABLE
EXCEPTION = _tkinter.EXCEPTION

_magic_re = None
_space_re = None

_magic_re = re.compile(r'([\\{}])')
_space_re = re.compile(r'([\s])', re.ASCII)
def _get_magic_re():
"""Internal function."""
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@danielhollas danielhollas Apr 12, 2026

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this docstring (and below) doesn't add any info. (you can say that this function hides the re import to make it lazy

Suggested change
"""Internal function."""

global _magic_re
if _magic_re is None:
_magic_re = re.compile(r'([\\{}])')
return _magic_re

def _get_space_re():
"""Internal function."""
global _space_re
if _space_re is None:
_space_re = re.compile(r'([\s])', re.ASCII)
return _space_re

def _join(value):
"""Internal function."""
return ' '.join(map(_stringify, value))


def _stringify(value):
"""Internal function."""
if isinstance(value, (list, tuple)):
if len(value) == 1:
value = _stringify(value[0])
if _magic_re.search(value):
if _get_magic_re().search(value):
value = '{%s}' % value
else:
value = '{%s}' % _join(value)
Expand All @@ -76,14 +86,14 @@ def _stringify(value):
value = str(value)
if not value:
value = '{}'
elif _magic_re.search(value):
elif _get_magic_re().search(value):
# add '\' before special characters and spaces
value = _magic_re.sub(r'\\\1', value)
value = _get_magic_re().sub(r'\\\1', value)
value = value.replace('\n', r'\n')
value = _space_re.sub(r'\\\1', value)
value = _get_space_re().sub(r'\\\1', value)
if value[0] == '"':
value = '\\' + value
elif value[0] == '"' or _space_re.search(value):
elif value[0] == '"' or _get_space_re().search(value):
value = '{%s}' % value
return value

Expand Down Expand Up @@ -5094,6 +5104,7 @@ def _test():

__all__ = [name for name, obj in globals().items()
if not name.startswith('_') and not isinstance(obj, types.ModuleType)
and not isinstance(obj, types.LazyImportType)
and name not in {'wantobjects'}]

if __name__ == '__main__':
Expand Down
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2026-04-11-18-49-40.gh-issue-109653.VXU-w8.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Reduce the import time of :mod:`tkinter` with lazy imports. Patch by Rihaan
Meher.
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