bpo-16500: Don't use string constants for os.register_at_fork() behavior (#1834)
Instead use keyword only arguments to os.register_at_fork for each of the scenarios.
Updates the documentation for clarity.
diff --git a/Lib/random.py b/Lib/random.py
index 52df7d8..b54d524 100644
--- a/Lib/random.py
+++ b/Lib/random.py
@@ -765,7 +765,7 @@
getrandbits = _inst.getrandbits
if hasattr(_os, "fork"):
- _os.register_at_fork(_inst.seed, when='child')
+ _os.register_at_fork(after_in_child=_inst.seed)
if __name__ == '__main__':
diff --git a/Lib/test/test_posix.py b/Lib/test/test_posix.py
index a72f83c..412b079 100644
--- a/Lib/test/test_posix.py
+++ b/Lib/test/test_posix.py
@@ -189,19 +189,41 @@
self.assertEqual(pid, res.si_pid)
@unittest.skipUnless(hasattr(os, 'fork'), "test needs os.fork()")
- def test_register_after_fork(self):
+ def test_register_at_fork(self):
+ with self.assertRaises(TypeError, msg="Positional args not allowed"):
+ os.register_at_fork(lambda: None)
+ with self.assertRaises(TypeError, msg="Args must be callable"):
+ os.register_at_fork(before=2)
+ with self.assertRaises(TypeError, msg="Args must be callable"):
+ os.register_at_fork(after_in_child="three")
+ with self.assertRaises(TypeError, msg="Args must be callable"):
+ os.register_at_fork(after_in_parent=b"Five")
+ with self.assertRaises(TypeError, msg="Args must not be None"):
+ os.register_at_fork(before=None)
+ with self.assertRaises(TypeError, msg="Args must not be None"):
+ os.register_at_fork(after_in_child=None)
+ with self.assertRaises(TypeError, msg="Args must not be None"):
+ os.register_at_fork(after_in_parent=None)
+ with self.assertRaises(TypeError, msg="Invalid arg was allowed"):
+ # Ensure a combination of valid and invalid is an error.
+ os.register_at_fork(before=None, after_in_parent=lambda: 3)
+ with self.assertRaises(TypeError, msg="Invalid arg was allowed"):
+ # Ensure a combination of valid and invalid is an error.
+ os.register_at_fork(before=lambda: None, after_in_child='')
+ # We test actual registrations in their own process so as not to
+ # pollute this one. There is no way to unregister for cleanup.
code = """if 1:
import os
r, w = os.pipe()
fin_r, fin_w = os.pipe()
- os.register_at_fork(lambda: os.write(w, b'A'), when='before')
- os.register_at_fork(lambda: os.write(w, b'B'), when='before')
- os.register_at_fork(lambda: os.write(w, b'C'), when='parent')
- os.register_at_fork(lambda: os.write(w, b'D'), when='parent')
- os.register_at_fork(lambda: os.write(w, b'E'), when='child')
- os.register_at_fork(lambda: os.write(w, b'F'), when='child')
+ os.register_at_fork(before=lambda: os.write(w, b'A'))
+ os.register_at_fork(after_in_parent=lambda: os.write(w, b'C'))
+ os.register_at_fork(after_in_child=lambda: os.write(w, b'E'))
+ os.register_at_fork(before=lambda: os.write(w, b'B'),
+ after_in_parent=lambda: os.write(w, b'D'),
+ after_in_child=lambda: os.write(w, b'F'))
pid = os.fork()
if pid == 0:
diff --git a/Lib/threading.py b/Lib/threading.py
index 2eaf49a..92c2ab3 100644
--- a/Lib/threading.py
+++ b/Lib/threading.py
@@ -1359,5 +1359,5 @@
assert len(_active) == 1
-if hasattr(_os, "fork"):
- _os.register_at_fork(_after_fork, when="child")
+if hasattr(_os, "register_at_fork"):
+ _os.register_at_fork(after_in_child=_after_fork)