From 1dcb46104f8a66d3da78ddfd6004028f6e6bbd0f Mon Sep 17 00:00:00 2001 From: "Miss Islington (bot)" <31488909+miss-islington@users.noreply.github.com> Date: Wed, 13 Mar 2024 12:09:52 +0100 Subject: [PATCH] [3.11] gh-111307: Update design FAQ 'switch' entry (GH-115899) (#116704) (cherry picked from commit 43986f55671ba2f7b08f8c5cea69aa136a093697) Co-authored-by: Terry Jan Reedy --- Doc/faq/design.rst | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/Doc/faq/design.rst b/Doc/faq/design.rst index d0c136deaba..00b1ef69946 100644 --- a/Doc/faq/design.rst +++ b/Doc/faq/design.rst @@ -258,9 +258,11 @@ is evaluated in all cases. Why isn't there a switch or case statement in Python? ----------------------------------------------------- -You can do this easily enough with a sequence of ``if... elif... elif... else``. -For literal values, or constants within a namespace, you can also use a -``match ... case`` statement. +In general, structured switch statements execute one block of code +when an expression has a particular value or set of values. +Since Python 3.10 one can easily match literal values, or constants +within a namespace, with a ``match ... case`` statement. +An older alternative is a sequence of ``if... elif... elif... else``. For cases where you need to choose from a very large number of possibilities, you can create a dictionary mapping case values to functions to call. For @@ -289,6 +291,9 @@ It's suggested that you use a prefix for the method names, such as ``visit_`` in this example. Without such a prefix, if values are coming from an untrusted source, an attacker would be able to call any method on your object. +Imitating switch with fallthrough, as with C's switch-case-default, +is possible, much harder, and less needed. + Can't you emulate threads in the interpreter instead of relying on an OS-specific thread implementation? --------------------------------------------------------------------------------------------------------