tree bd8f4561047f7376ad862aa59af3d0f51c73dd2e
parent 1bcc32f0620d2e99649a6d423284d9496b7b3548
author Daniel Fortunov <asqui@users.noreply.github.com> 1591820809 +0100
committer GitHub <noreply@github.com> 1591820809 -0700
gpgsig -----BEGIN PGP SIGNATURE-----
 
 wsBcBAABCAAQBQJe4UIJCRBK7hj4Ov3rIwAAdHIIABqmWi4dqUMOYTlAdjLHA6Dl
 462kir4g8uCfUBfSxLk7hjzcEvbjVWT6/DWrVmIQbB7HTXc+fX6YLAgp7gimjtLL
 zwDmGNp1ZxXPQW3sWIzbcqn9025a/63l7nqC6ZqnSMbpj1XhFbPps+4icAQ22apU
 H+ReYXTA8ukTI9UbYPHVSIeZsjopiyEhHfd7OKRsdDrcf8Qp3NthM/j4w7VqID3n
 3iHH8xPhph8pTIo5bCU1kAzslWylTmdKLBZ3SJRS2rxBq5e3XB51FZ+ml/4i1Dbe
 GRuEHJpe7nH2hA58lZhMiGPd0slr+54IJH+uU8b58bQH/XR+0q6snaeaFcOZtNI=
 =UBJk
 -----END PGP SIGNATURE-----
 

bpo-40895: Update weakref documentation to remove old warnings (GH-20687)


The doccumentation at https://docs.python.org/3.10/library/weakref.html cautions that the `WeakKeyDictionary` and `WeakValueDictionary` are susceptible to the problem of dictionary mutation during iteration.

These notes present the user with a problem that has no easy solution.

I dug into the implementation and found that fortunately, Antoine Pitrou already addressed this challenge (10 years ago!) by introducing an `_IterationGuard` context manager to the implementation, which delays mutation while an iteration is in progress.

I asked for confirmation and @pitrou agreed that these notes could be removed:
https://github.com/python/cpython/commit/c1baa601e2b558deb690edfdf334fceee3b03327#commitcomment-39514438