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

New
mikecargal
Title: Hands-On Rust (Chapter 11: prefab) Just played a couple of amulet-less games. With a bit of debugging, I believe that your can_p...
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
cro
I am working on the “Your Turn” for chapter one and building out the restart button talked about on page 27. It recommends looking into ...
New
rmurray10127
Title: Intuitive Python: docker run… denied error (page 2) Attempted to run the docker command in both CLI and Powershell PS C:\Users\r...
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
AndyDavis3416
@noelrappin Running the webpack dev server, I receive the following warning: ERROR in tsconfig.json TS18003: No inputs were found in c...
New
adamwoolhether
I’m not quite sure what’s going on here, but I’m unable to have to containers successfully complete the Readiness/Liveness checks. I’m im...
New
SlowburnAZ
Getting an error when installing the dependencies at the start of this chapter: could not compile dependency :exla, "mix compile" failed...
New
dachristenson
@mfazio23 Android Studio will not accept anything I do when trying to use the Transformations class, as described on pp. 140-141. Googl...
New

Other popular topics Top

AstonJ
Or looking forward to? :nerd_face:
490 12945 266
New
PragmaticBookshelf
Design and develop sophisticated 2D games that are as much fun to make as they are to play. From particle effects and pathfinding to soci...
New
AstonJ
Just done a fresh install of macOS Big Sur and on installing Erlang I am getting: asdf install erlang 23.1.2 Configure failed. checking ...
New
AstonJ
I have seen the keycaps I want - they are due for a group-buy this week but won’t be delivered until October next year!!! :rofl: The Ser...
New
Exadra37
I am asking for any distro that only has the bare-bones to be able to get a shell in the server and then just install the packages as we ...
New
foxtrottwist
A few weeks ago I started using Warp a terminal written in rust. Though in it’s current state of development there are a few caveats (tab...
New
AstonJ
We’ve talked about his book briefly here but it is quickly becoming obsolete - so he’s decided to create a series of 7 podcasts, the firs...
New
Help
I am trying to crate a game for the Nintendo switch, I wanted to use Java as I am comfortable with that programming language. Can you use...
New
New
PragmaticBookshelf
Author Spotlight: VM Brasseur @vmbrasseur We have a treat for you today! We turn the spotlight onto Open Source as we sit down with V...
New

Sub Categories: