From dedfaa384408b266c461fea45fee936989bb151b Mon Sep 17 00:00:00 2001 From: Aleksey Kladov Date: Thu, 15 Oct 2020 12:21:38 +0200 Subject: Cleanup alloc advice --- docs/dev/style.md | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'docs/dev/style.md') diff --git a/docs/dev/style.md b/docs/dev/style.md index 435de63e3..20f1b6253 100644 --- a/docs/dev/style.md +++ b/docs/dev/style.md @@ -248,6 +248,8 @@ fn frbonicate(f: impl AsRef) { # Premature Pessimization +## Avoid Allocations + Avoid writing code which is slower than it needs to be. Don't allocate a `Vec` where an iterator would do, don't allocate strings needlessly. @@ -267,6 +269,8 @@ if words.len() != 2 { } ``` +## Push Allocations to the Call Site + If allocation is inevitable, let the caller allocate the resource: ```rust @@ -282,6 +286,9 @@ fn frobnicate(s: &str) { } ``` +This is better because it reveals the costs. +It is also more efficient when the caller already owns the allocation. + ## Collection types Prefer `rustc_hash::FxHashMap` and `rustc_hash::FxHashSet` instead of the ones in `std::collections`. -- cgit v1.2.3