From 97c493dd3543c7c3bb5319587c162f46271d4c5d Mon Sep 17 00:00:00 2001 From: Samuel Sloniker Date: Thu, 10 Nov 2022 20:16:16 -0800 Subject: [PATCH] gh-84522: Add for-loop to apply-method-to-sequence FAQ (#94660) --- Doc/faq/programming.rst | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/Doc/faq/programming.rst b/Doc/faq/programming.rst index f3c5b0f7649..584d33e9622 100644 --- a/Doc/faq/programming.rst +++ b/Doc/faq/programming.rst @@ -1279,13 +1279,25 @@ Or, you can use an extension that provides a matrix datatype; `NumPy `_ is the best known. -How do I apply a method to a sequence of objects? -------------------------------------------------- +How do I apply a method or function to a sequence of objects? +------------------------------------------------------------- -Use a list comprehension:: +To call a method or function and accumulate the return values is a list, +a :term:`list comprehension` is an elegant solution:: result = [obj.method() for obj in mylist] + result = [function(obj) for obj in mylist] + +To just run the method or function without saving the return values, +a plain :keyword:`for` loop will suffice:: + + for obj in mylist: + obj.method() + + for obj in mylist: + function(obj) + .. _faq-augmented-assignment-tuple-error: Why does a_tuple[i] += ['item'] raise an exception when the addition works?