From 43979fad904bcc343f90cb526faa526c45fcbfa4 Mon Sep 17 00:00:00 2001 From: Jelle Zijlstra Date: Thu, 26 Sep 2024 11:50:31 -0700 Subject: [PATCH] Programming FAQ: Mention object.__setattr__ as a technique for delegation (#124617) This is used for example by threading.local in the stdlib. --- Doc/faq/programming.rst | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/Doc/faq/programming.rst b/Doc/faq/programming.rst index 4a6f1ca57d8..fa7b22bde1d 100644 --- a/Doc/faq/programming.rst +++ b/Doc/faq/programming.rst @@ -1613,9 +1613,16 @@ method too, and it must do so carefully. The basic implementation of self.__dict__[name] = value ... -Most :meth:`!__setattr__` implementations must modify -:attr:`self.__dict__ ` to store -local state for self without causing an infinite recursion. +Many :meth:`~object.__setattr__` implementations call :meth:`!object.__setattr__` to set +an attribute on self without causing infinite recursion:: + + class X: + def __setattr__(self, name, value): + # Custom logic here... + object.__setattr__(self, name, value) + +Alternatively, it is possible to set attributes by inserting +entries into :attr:`self.__dict__ ` directly. How do I call a method defined in a base class from a derived class that extends it?