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
telemachus
Python Testing With Pytest - Chapter 2, warnings for “unregistered custom marks” While running the smoke tests in Chapter 2, I get these...
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
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
curtosis
Running mix deps.get in the sensor_hub directory fails with the following error: ** (Mix) No SSH public keys found in ~/.ssh. An ssh aut...
New
brunogirin
When trying to run tox in parallel as explained on page 151, I got the following error: tox: error: argument -p/–parallel: expected one...
New
adamwoolhether
Is there any place where we can discuss the solutions to some of the exercises? I can figure most of them out, but am having trouble with...
New
creminology
Skimming ahead, much of the following is explained in Chapter 3, but new readers (like me!) will hit a roadblock in Chapter 2 with their ...
New
dtonhofer
@parrt In the context of Chapter 4.3, the grammar Java.g4, meant to parse Java 6 compilation units, no longer passes ANTLR (currently 4....
New
New

Other popular topics Top

Devtalk
Hello Devtalk World! Please let us know a little about who you are and where you’re from :nerd_face:
New
Devtalk
Reading something? Working on something? Planning something? Changing jobs even!? If you’re up for sharing, please let us know what you’...
1050 21151 394
New
AstonJ
What chair do you have while working… and why? Is there a ‘best’ type of chair or working position for developers?
New
Exadra37
I am thinking in building or buy a desktop computer for programing, both professionally and on my free time, and my choice of OS is Linux...
New
AstonJ
I ended up cancelling my Moonlander order as I think it’s just going to be a bit too bulky for me. I think the Planck and the Preonic (o...
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
PragmaticBookshelf
Author Spotlight Mike Riley @mriley This month, we turn the spotlight on Mike Riley, author of Portable Python Projects. Mike’s book ...
New
First poster: AstonJ
Jan | Rethink the Computer. Jan turns your computer into an AI machine by running LLMs locally on your computer. It’s a privacy-focus, l...
New
AstonJ
This is a very quick guide, you just need to: Download LM Studio: https://lmstudio.ai/ Click on search Type DeepSeek, then select the o...
New
PragmaticBookshelf
Fight complexity and reclaim the original spirit of agility by learning to simplify how you develop software. The result: a more humane a...
New

Sub Categories: