Rust Programming

Let's say I have a struct Event which implements the method permalink:

struct Event {
    base_url: String,
    rel_permalink: String,
    permalink: String,
    title: String,
}

impl Event {
    fn permalink(&self) -> String {
        let permalink = format!("{}{}", self.base_url, self.rel_permalink);
        permalink
    }
}

The method takes 2 fields of the struct and the target would be to return the definition of another field.

Later I instantiate an event1: Event:

let event1 = Event {
                base_url: base_url,
                rel_permalink: rel_permalink.to_string(),
                title: node.value().name().to_string(),
                permalink = permalink(),
            };

Essentially I would like the field permalink to be the value returned by the method permalink, is something like this possible, is this correct? I couldn't find something similar in the docs..

Pheraps using an associated function as constructor would be a better way to handle a similar situation?

Thank you so much!

fn get_links(link_nodes: Select) -> Option<String> {

        let mut rel_permalink: Option<String> = for node in link_nodes {
            link = String::from(node.value().attr("href")?);

            return Some(link);
        };

        Some(rel_permalink)
    }

This is what I'm trying to do, and I've been stuck with this code for an hour, I simply don't know how to put this function togheter.. Essentially I would like to take some link_nodes and just return the link String, but I'm stuck in the use of Option with the ? operator.. Pheraps trying to write it with match would clear things out(?)

Also I come from JavaScript in which expressions do not have their own scope, meaning I'm having troubles to understand how to get out a variable from a for loop, should I initialize the rel_permalink variable as the for loop result?

This are the errors i get:

error[E0308]: mismatched types
  --> src/main.rs:55:49
   |
55 |           let mut rel_permalink: Option<String> = for node in link_nodes {
   |  _________________________________________________^
56 | |             link = String::from(node.value().attr("href")?);
57 | |
58 | |             return Some(link);
59 | |         };
   | |_________^ expected `Option<String>`, found `()`
   |
   = note:   expected enum `Option<String>`
           found unit type `()`
note: the function expects a value to always be returned, but loops might run zero times
  --> src/main.rs:55:49
   |
55 |         let mut rel_permalink: Option<String> = for node in link_nodes {
   |                                                 ^^^^^^^^^^^^^^^^^^^^^^ this might have zero elements to iterate on
56 |             link = String::from(node.value().attr("href")?);
   |                                                          - if the loop doesn't execute, this value would never get returned
57 |
58 |             return Some(link);
   |             ----------------- if the loop doesn't execute, this value would never get returned
   = help: return a value for the case when the loop has zero elements to iterate on, or consider changing the return type to account for that possibility

gccrs is a work-in-progress alternative compiler for Rust being developed as part of the GCC project. GCC is a collection of compilers for various programming languages that all share a common compilation framework. You may have heard about gccgo, gfortran, or g++, which are all binaries within that project, the GNU Compiler Collection. The aim of gccrs is to add support for the Rust programming language to that collection, with the goal of having the exact same behavior as rustc.

CXX-Qt is a set of Rust crates for creating bidirectional Rust ⇄ C++ bindings with Qt. It supports integrating Rust into C++ applications using CMake or building Rust applications with Cargo. CXX-Qt provides tools for implementing QObject subclasses in Rust that can be used from C++, QML, and JavaScript.

For 0.7, we have stabilized the cxx-qt bridge macro API and there have been many internal refactors to ensure that we have a consistent baseline to support going forward. We encourage developers to reach out if they find any unclear areas or missing features, to help us ensure a roadmap for them, as this may be the final time we can adapt the API. In the next releases, we’re looking towards stabilizing the cxx-qt-build and getting the cxx-qt-lib APIs ready for 1.0.

After almost 3 years of work, I've finally managed to get this project stable enough to release an alpha version!

I'm proud to present Managarr - A TUI and CLI for managing your Servarr instances! At the moment, the alpha version only supports Radarr.

Not all features are implemented for the alpha version, like managing quality profiles or quality definitions, etc.

Here's some screenshots of the TUI:

Additionally, you can use it as a CLI for Radarr; For example, to search for a new film:

managarr radarr search-new-movie --query "star wars"

Or you can add a new movie by its TMDB ID:

managarr radarr add movie --tmdb-id 1895 --root-folder-path /nfs/movies --quality-profile-id 1

All features available in the TUI are also available via the CLI.

Hi! I'm trying to learn Rust, as a little project, I'm trying to build a web scraper that will scrape some content and rebuild it with a static site generator, or using it for making POST requests.

I'm still at a very early stage and I still don't know much, the simplest error handling strategy I know is using match with Result.

To my eyes, this syntax looks correct, but also looks kind of a lot of lines for a simple http request.

I know the reqwest docs suggest to handle errors with the ? operator, which I don't know yet, therefore I'm just using what I know now.

fn get_document(permalink: String) -> Html {
        let html_content_result = reqwest::blocking::get(&permalink);
        let html_content = match html_content_result {
            Ok(response) => response,
            Err(error) => panic!("There was an error making the request: {:?}", error),
        };

        let html_content_text_result = html_content.text();
        let html_content_text = match html_content_text_result {
            Ok(text) => text,
            Err(error) =>
                panic!(
                    "There was an error getting the html text from the content of response: :{:?}",
                    error
                ),
        };

        let document = Html::parse_document(&html_content_text);

        document
    }

As for my understanding, this is what I'm doing here: I'm making an http request, if i get a Response, I try to get the text out of the response body, otherwise I handle the error by panicking with a custom message. Getting the text out of the request body is another passage that requires error handling, therefore I use the match expression again to get the text out and handle the possible error (In what circumstances can extracting the text of a response body fail?).

Then I can finally parse the document and return it!

I wonder if it is a correct and understandable way of doing what I've in mind.

Do you think this would be a suitable project for someone who is at chapter 7 of the Rust book? I feel like i actually need to build somethiong before keep going with the theory!

I would like to share a bash script I made for when you want to simply run a rust script once and delete it. Instead of having compile the script with rustc, running the binary and then deleting the binary, you can achive all of this with this bash script below.

The first argument will be the rust script file name. The .rs file extension is optional. The rest of the arguments are passed into the executed binary.

Simply name the bash script to something like rust-run.sh.

#!/bin/bash

#Get file path from first parameter
path=$(dirname "$1")

#Get file name from first parameter
fileName=$(basename "$1")
fileName="${fileName%'.rs'}"

#Compile executable and save it in the same directory as the rust script
rustc "${path}/${fileName}.rs" -o "${path}/${fileName}"

#If rustc commands retuned any errors, unable to compile the rust script
if [ $? -ne 0 ]; then
    return
fi

#Execute compilled executable and pass the rest of the parameters into the executable
"${path}/${fileName}" ${*:2}

#Delete compillled executable
rm "${path}/${fileName}"

If someone wants to rewrite this in rust or add these features into the rustc, feel free to do so.

This release contains numerous bug fixes and minor improvements. Thanks to Kalcifer for reporting many of these.

• LaTeX formatting is now supported to handle mathematics (thanks Silver-Sorbet)
• The editor now has a live preview of rendered markdown
• Better layout for edit history
• Fixed user links in edit history
• Edits are now correctly sorted by date
• Removed maximum width for page
• Render markdown titles smaller than page title
• Disable markdown plugins for url shortening and smartquotes
• Resize article edit input based on length

More details and download

(I'm just starting off with rust, so please be patient)

Is there an idiomatic way of writing the following as a one-liner, somehow informing rustc that it should keep the PathBuf around?

// nevermind the fully-qualified names
// they are there to clarify the code
// (that's what I hope at least)

let dir: std::path::PathBuf = std::env::current_dir().unwrap();
let dir: &std::path::Path   = dir.as_path();

// this won't do:
// let dir = std::env::current_dir().unwrap().as_path();

I do understand why rust complains that "temporary value dropped while borrowed" (I mean, the message says it all), but, since I don't really need the PathBuf for anything else, I was wondering if there's an idiomatic to tell rust that it should extend its life until the end of the code block.

Rust ownership is a fundamental part of the language.

I’ve summarized the basic concepts here as a learning exercise for myself.

I’m sharing this to gather feedback, corrections, and suggestions.

Feel free to offer improvements wherever needed!

We also have documentation to setup the dev environment: https://join-lemmy.org/docs/contributors/02-local-development.html

If you have questions, feel free to ask here, in the relevant issue or in matrix.

Which of these code styles do you find preferable?

First option using mut with constructor in the beginning:

  let mut post_form = PostInsertForm::new(
    data.name.trim().to_string(),
    local_user_view.person.id,
    data.community_id,
  );
  post_form.url = url.map(Into::into);
  post_form.body = body;
  post_form.alt_text = data.alt_text.clone();
  post_form.nsfw = data.nsfw;
  post_form.language_id = language_id;

Second option without mut and constructor at the end:

  let post_form = PostInsertForm {
    url: url.map(Into::into),
    body,
    alt_text: data.alt_text.clone(),
    nsfw: data.nsfw,
    language_id,
    ..PostInsertForm::new(
      data.name.trim().to_string(),
      local_user_view.person.id,
      data.community_id,
    )
  };

You can see the full PR here: https://github.com/LemmyNet/lemmy/pull/5037/files

link to crate : https://crates.io/crates/st7567_rs

Rust Project goals for 2024

https://blog.rust-lang.org/2024/08/12/Project-goals.html

cc: @[email protected]

#rust folks it's supposed to throw this error without lazy_static crate , but it doesn't?
https://git.sr.ht//~carnotweat/morning-rust/tree/main/item/sum.rs#L14
cc @rust @learningrustandlemmy

cross-posted from: https://lemmy.world/post/18129059

This feels like it should already be a feature in a terminal. But I didn't find anything that let me do this efficiently.

I had a rust library for converting list like 1-4,8-10 into vectors, but thought I'd expand it into a command line command as well, as it is really useful when I want to run batch commands in parallel using templates.

I wanted to share it since it might be a useful simple command for many people.

Hi all,

mpv communities seem to be tiny in lemmy, so I'm sharing it here.

This is a program I made for music control from local network.

You can run it in a computer with some local media files, or youtube links or any other links yt-dlp supports. And then with the server, you can control the media player and the playlist from any devices in your local network. So that you can just show a QR code or something to house guests for parties, or have it bookmarked within family to control the music.

I wanted to make something similar to how youtube app let's you play in TV and such, but my skills were not enough to do that. So I tried a simple alternative that works with computers. In an ideal world, I could make "Play with local mpv server" option come while on other android apps, but I have zero experience in android app development and it looks complicated.

I know some other programs also give option to control media, but I wanted to give it a go with a simple implementation. Making the web-server was a tricky part. Only tutorial from the rust book was useful here as every other web server developement in rust seems to be async ones using libraries so I would have to make a complicated system to communicate with the mpv. Using the simple Tcp connection let me make a thread with mpv instance in the scope. I do need to support https and file uploads and other things, but I haven't had any luck finding a solution that works with simple Tcp connection like in the tutorial. Let me know if you know anything.

Github: https://github.com/Atreyagaurav/local-mpv

For context, I am using the libraries bevy and print_typewriter.

I noticed that before the program even starts, I am able to type in characters. This is bad, since when I ask for the user's input, the previous characters are included inside of it.

How do I make sure that only the user's input after the program starts, and after I print a question gets in?

In which BurntSushi does date/time handling. Reddit discussion, HN discussion.

Before someone asks:

• Comparison with other Rust datetime crates
• Why build another datetime library?
• Why not contribute to an existing library instead of building a new one?

This would entail:

• Pulling in the ClearUrls rules as a git submodule.
• Reading / transforming the json there into Rust structs.
• Creating a Rust crate that runs a .clean(input_url) -> String

Lemmy issue: https://github.com/LemmyNet/lemmy/issues/4905

• Added type diesel_async::pooled_connection::mobc::PooledConnection
• MySQL/MariaDB now use CLIENT_FOUND_ROWS capability to allow consistent behaviour with PostgreSQL regarding return value of UPDATe commands.
• The minimal supported rust version is now 1.78.0
• Add a SyncConnectionWrapper type that turns a sync connection into an async one. This enables SQLite support for diesel-async
• Add support for diesel::connection::Instrumentation to support logging and other instrumentation for any of the provided connection impls.
• Bump minimal supported mysql_async version to 0.34

A special thanks goes to @momobel and Wattsense for contributing the SyncConnectionWrapper implementation.

To support future development efforts, please consider sponsoring me on GitHub.

Full Changelog: v0.4.0...v0.5.0

It's less than two weeks until our next Rust and NixOS meetup in Mannheim, Germany. We're meeting on the 16th of July at the Mafinex technology center close to the main station. If you want to join us, please sign up for the event on Mobilizon (no account required) or Meetup.com.

https://rheinneckar.events/events/9d740b89-7713-4e19-a112-45aff1670f0f

https://www.meetup.com/hackschool-rhein-neckar/events/301504325/

As first talk, we will hear Andre Dossinger on "Using NixOS for Pragmatical Self-hosting", where he will show us how NixOS can be used in a problem oriented manner to preserve privacy and make complex setups manageable. Questions and discussions are highly encouraged!

Then, we will hear Benjamin Sparks on "Reading from Streams and Writing to Sinks" using Rust and Tokio, with a focus on low runtime overhead, safe buffer management, and robust error handling. He will show us the types and traits Tokio leverages to efficiently decode bytes and encode structured data in a type-safe manner is presented, and give us a practical demonstration of codecs for two different protocols.

Finally, Stefan Machmeier of the EMCL at Heidelberg University will give us an introduction to Nix Flakes, the experimental dependency management system built into Nix since version 2.4 that can be used for reusable Nix libraries as well as your own Nix packages and NixOS configurations.

The talks will be recorded and uploaded after the meetup.

cross-posted from: https://programming.dev/post/16349359

July 2, 2024

Sylvain Kerkour writes:

Rust adoption is stagnating not because it's missing some feature pushed by programming language theory enthusiasts, but because of a lack of focus on solving the practical problems that developers are facing every day.

... no company outside of AWS is making SDKs for Rust ... it has no official HTTP library.

As a result of Rust's lack of official packages, even its core infrastructure components need to import hundreds of third-party crates.

• cargo imports over 400 crates.

• crates.io has over 500 transitive dependencies.

...the offical libsignal (from the Signal messaging app) uses 500 third-party packages.

... what is really inside these packages. It has been found last month that among the 999 most popular packages on crates.io, the content of around 20% of these doesn't even match the content of their Git repository.

...how I would do it (there may be better ways):

A stdx (for std eXtended) under the rust-lang organization containing the most-needed packages. ... to make it secure: all packages in stdx can only import packages from std or stdx. No third-party imports. No supply-chain risks.

[stdx packages to include, among others]:

gzip, hex, http, json, net, rand

Read Rust has a HUGE supply chain security problem

Submitter's note:

I find the author's writing style immature, sensationalist, and tiresome, but they raise a number of what appear to be solid points, some of which are highlighted above.