mikecargal

mikecargal

Hands-on Rust: clone_dirty cloning HashSet

Title: Hands-On Rust (Chapter 10)

This has been bugging me a bit since coding it, so I tried the change and it seems to work.

Isn’t it a bit expensive to clone a HashSet that you intend to immediately replace?

I tried the following change to clone_dirty(&self) -> Self

    pub fn clone_dirty(&self) -> Self {
        // let mut cloned = self.clone(); // TODO: isn't this expensive??
        // cloned.is_dirty = true;
        // cloned
        Self {
            visible_tiles: HashSet::new(),
            radius: self.radius,
            is_dirty: true,
        }
    }

Game play seems to be working fine so far. I’m assuming that creating a new HashSet is less expensive than closing a populated HashSet. That also raised the question for me as to whether visible_tiles should be Option instead and the None would serve the same purpose as is_dirty. Maybe I’ll see that this is a bad idea as I progress…

Marked As Solved

herbert

herbert

Author of Hands-on Rust

That’s a good point; clone can be expensive (it’s remarkable how well LLVM optimizes it out, especially on release builds). There’s a bit of compiler magic that notices that it’s basically a set of memcpy calls under the hood, and elides them. I like your approach better, though - it’s dangerous to rely on the compiler noticing an optimization when you can tell it what you want.

Adding an is_visible method is also a great idea. I’ll see if I can refactor the book code a little.

I’ll try and merge this into the next beta. Thank you!

Where Next?

Popular Pragmatic Bookshelf topics Top

belgoros
Following the steps described in Chapter 6 of the book, I’m stuck with running the migration as described on page 84: bundle exec sequel...
New
jesse050717
Title: Web Development with Clojure, Third Edition, pg 116 Hi - I just started chapter 5 and I am stuck on page 116 while trying to star...
New
Alexandr
Hi everyone! There is an error on the page 71 in the book “Programming machine learning from coding to depp learning” P. Perrotta. You c...
New
simonpeter
When I try the command to create a pair of migration files I get an error. user=> (create-migration "guestbook") Execution error (Ill...
New
mikecargal
Title: Hands-on Rust: question about get_component (page 295) (feel free to respond. “You dug you’re own hole… good luck”) I have somet...
New
gilesdotcodes
In case this helps anyone, I’ve had issues setting up the rails source code. Here were the solutions: In Gemfile, change gem 'rails' t...
New
leba0495
Hello! Thanks for the great book. I was attempting the Trie (chap 17) exercises and for number 4 the solution provided for the autocorre...
New
nicoatridge
Hi, I have just acquired Michael Fazio’s “Kotlin and Android Development” to learn about game programming for Android. I have a game in p...
New
Charles
In general, the book isn’t yet updated for Phoenix version 1.6. On page 18 of the book, the authors indicate that an auto generated of ro...
New
davetron5000
Hello faithful readers! If you have tried to follow along in the book, you are asked to start up the dev environment via dx/build and ar...
New

Other popular topics Top

AstonJ
What chair do you have while working… and why? Is there a ‘best’ type of chair or working position for developers?
New
ohm
Which, if any, games do you play? On what platform? I just bought (and completed) Minecraft Dungeons for my Nintendo Switch. Other than ...
New
brentjanderson
Bought the Moonlander mechanical keyboard. Cherry Brown MX switches. Arms and wrists have been hurting enough that it’s time I did someth...
New
AstonJ
Curious to know which languages and frameworks you’re all thinking about learning next :upside_down_face: Perhaps if there’s enough peop...
New
AstonJ
I’ve been hearing quite a lot of comments relating to the sound of a keyboard, with one of the most desirable of these called ‘thock’, he...
New
AstonJ
If you are experiencing Rails console using 100% CPU on your dev machine, then updating your development and test gems might fix the issu...
New
PragmaticBookshelf
Build efficient applications that exploit the unique benefits of a pure functional language, learning from an engineer who uses Haskell t...
New
PragmaticBookshelf
Author Spotlight Mike Riley @mriley This month, we turn the spotlight on Mike Riley, author of Portable Python Projects. Mike’s book ...
New
AstonJ
Curious what kind of results others are getting, I think actually prefer the 7B model to the 32B model, not only is it faster but the qua...
New
RobertRichards
Hair Salon Games for Girls Fun Girls Hair Saloon game is mainly developed for kids. This game allows users to select virtual avatars to ...
New

Sub Categories: