Mary  Turcotte

Mary Turcotte

1665992580

A Couple Of Extra Ownership and Borrowing Samples In Rust

Rust Extra Ownership & Borrowing Samples

This repo contains some more samples for learning basic Rust Ownership and Borrowing stuff.

Follow allong each lesson in src/bin, reading the header comments in the file.

Not all code is running correctly, and this is intentional. What I wanted was to show some counter examples. Things that we must NOT do in order to write programs in Rust.

Have fun!

RUST BASICS

This is a project that demonstrates most of the essential rust notation.

There are also code that illustrates some of the most important concepts regarding ownership and borrowing, which makes the rust language one of the most interesting and intriguing programming languages lately.

I really enjoyed going through all these learnings, but I must confess that rust lang makes me a little dizzy sometimes.

BUILDING:

cargo build

RUNNING

cargo run

How to work with this project

The first thing to notice is that many warnings will be issued by the first time you run/compile this project.

That is because there are many unused variables. They exist so that one could learn different rust notations.

Another important thing for choosing what to learn is:

The src/bin directory has many files. They are numbered and each one has a main() function.

You should choose which concept to go through. Just pick a file by name and run it, change it, read it, play with it.

You should always execute a file and read the code, possibly following with a debugger.

There are also several code lines that are commented.

This is to remind myself that some ways of writing rust is wrong. Do not remove those commented lines if you also want to be reminded!

The IDEs I have used to create this project are Intellij and CLion. Any other IDE will be of use, though.

I hope some people could enjoy this repo as much as I did. And really have your mind going crazy around some of rust's concepts regarding memory management.

Any improvement is appreciated. Although there are more concepts and tools missing, this project here is actually done. I could create other projects to demonstrate more advanced rust concepts.

Cheers!

PS: I have written a more concise repo just to explain/demonstrate more about ownership/borrowing. Here it is: https://github.com/rsantiago/rust-ownership-samples

PS: If you want to know more about Rust's basic syntax, I would advise you to go through this other repo: https://github.com/rsantiago/rust_basics


Download Details:

Author: rsantiago
Source Code: https://github.com/rsantiago/rust-ownership-samples

#rust 

What is GEEK

Buddha Community

A Couple Of Extra Ownership and Borrowing Samples In Rust

Serde Rust: Serialization Framework for Rust

Serde

*Serde is a framework for serializing and deserializing Rust data structures efficiently and generically.*

You may be looking for:

Serde in action

Click to show Cargo.toml. Run this code in the playground.

[dependencies]

# The core APIs, including the Serialize and Deserialize traits. Always
# required when using Serde. The "derive" feature is only required when
# using #[derive(Serialize, Deserialize)] to make Serde work with structs
# and enums defined in your crate.
serde = { version = "1.0", features = ["derive"] }

# Each data format lives in its own crate; the sample code below uses JSON
# but you may be using a different one.
serde_json = "1.0"

 

use serde::{Serialize, Deserialize};

#[derive(Serialize, Deserialize, Debug)]
struct Point {
    x: i32,
    y: i32,
}

fn main() {
    let point = Point { x: 1, y: 2 };

    // Convert the Point to a JSON string.
    let serialized = serde_json::to_string(&point).unwrap();

    // Prints serialized = {"x":1,"y":2}
    println!("serialized = {}", serialized);

    // Convert the JSON string back to a Point.
    let deserialized: Point = serde_json::from_str(&serialized).unwrap();

    // Prints deserialized = Point { x: 1, y: 2 }
    println!("deserialized = {:?}", deserialized);
}

Getting help

Serde is one of the most widely used Rust libraries so any place that Rustaceans congregate will be able to help you out. For chat, consider trying the #rust-questions or #rust-beginners channels of the unofficial community Discord (invite: https://discord.gg/rust-lang-community), the #rust-usage or #beginners channels of the official Rust Project Discord (invite: https://discord.gg/rust-lang), or the #general stream in Zulip. For asynchronous, consider the [rust] tag on StackOverflow, the /r/rust subreddit which has a pinned weekly easy questions post, or the Rust Discourse forum. It's acceptable to file a support issue in this repo but they tend not to get as many eyes as any of the above and may get closed without a response after some time.

Download Details:
Author: serde-rs
Source Code: https://github.com/serde-rs/serde
License: View license

#rust  #rustlang 

Rust Ownership and Borrowing

This Rust programming language tutorial series is aimed at easing your training step by step. Rust is a systems level language aimed at speed and safety and can be run cross-platform, including embedded systems and even the browser with WebAssembly (WASM)! I use the VS Code development environment to help you learn the core topics. Please join me on this journey with this fantastic new programming language.

Topics include coding basics, hello world, primitives, cargo, toml, rustup, arrays, borrowing, shadowing, string vs str, tuples, enumerations (enums), println and so much more…all free on youtube!

#rust #ownership #borrowing

Moses  Jast

Moses Jast

1626347340

Ownership & Borrowing | Rust Tutorials - 04

Check out the entire playlist here: https://www.youtube.com/playlist?list=PLkO5ggdQuRaaeFke7nWS4ajhFVZ1biE7_

In this video, I will be covering the stack/heap memory model followed by Rust’s Ownership system and borrowing system.

#rust #ownership #borrowing

Mary  Turcotte

Mary Turcotte

1665992580

A Couple Of Extra Ownership and Borrowing Samples In Rust

Rust Extra Ownership & Borrowing Samples

This repo contains some more samples for learning basic Rust Ownership and Borrowing stuff.

Follow allong each lesson in src/bin, reading the header comments in the file.

Not all code is running correctly, and this is intentional. What I wanted was to show some counter examples. Things that we must NOT do in order to write programs in Rust.

Have fun!

RUST BASICS

This is a project that demonstrates most of the essential rust notation.

There are also code that illustrates some of the most important concepts regarding ownership and borrowing, which makes the rust language one of the most interesting and intriguing programming languages lately.

I really enjoyed going through all these learnings, but I must confess that rust lang makes me a little dizzy sometimes.

BUILDING:

cargo build

RUNNING

cargo run

How to work with this project

The first thing to notice is that many warnings will be issued by the first time you run/compile this project.

That is because there are many unused variables. They exist so that one could learn different rust notations.

Another important thing for choosing what to learn is:

The src/bin directory has many files. They are numbered and each one has a main() function.

You should choose which concept to go through. Just pick a file by name and run it, change it, read it, play with it.

You should always execute a file and read the code, possibly following with a debugger.

There are also several code lines that are commented.

This is to remind myself that some ways of writing rust is wrong. Do not remove those commented lines if you also want to be reminded!

The IDEs I have used to create this project are Intellij and CLion. Any other IDE will be of use, though.

I hope some people could enjoy this repo as much as I did. And really have your mind going crazy around some of rust's concepts regarding memory management.

Any improvement is appreciated. Although there are more concepts and tools missing, this project here is actually done. I could create other projects to demonstrate more advanced rust concepts.

Cheers!

PS: I have written a more concise repo just to explain/demonstrate more about ownership/borrowing. Here it is: https://github.com/rsantiago/rust-ownership-samples

PS: If you want to know more about Rust's basic syntax, I would advise you to go through this other repo: https://github.com/rsantiago/rust_basics


Download Details:

Author: rsantiago
Source Code: https://github.com/rsantiago/rust-ownership-samples

#rust 

Awesome  Rust

Awesome Rust

1654894080

Serde JSON: JSON Support for Serde Framework

Serde JSON

Serde is a framework for serializing and deserializing Rust data structures efficiently and generically.

[dependencies]
serde_json = "1.0"

You may be looking for:

JSON is a ubiquitous open-standard format that uses human-readable text to transmit data objects consisting of key-value pairs.

{
    "name": "John Doe",
    "age": 43,
    "address": {
        "street": "10 Downing Street",
        "city": "London"
    },
    "phones": [
        "+44 1234567",
        "+44 2345678"
    ]
}

There are three common ways that you might find yourself needing to work with JSON data in Rust.

  • As text data. An unprocessed string of JSON data that you receive on an HTTP endpoint, read from a file, or prepare to send to a remote server.
  • As an untyped or loosely typed representation. Maybe you want to check that some JSON data is valid before passing it on, but without knowing the structure of what it contains. Or you want to do very basic manipulations like insert a key in a particular spot.
  • As a strongly typed Rust data structure. When you expect all or most of your data to conform to a particular structure and want to get real work done without JSON's loosey-goosey nature tripping you up.

Serde JSON provides efficient, flexible, safe ways of converting data between each of these representations.

Operating on untyped JSON values

Any valid JSON data can be manipulated in the following recursive enum representation. This data structure is serde_json::Value.

enum Value {
    Null,
    Bool(bool),
    Number(Number),
    String(String),
    Array(Vec<Value>),
    Object(Map<String, Value>),
}

A string of JSON data can be parsed into a serde_json::Value by the serde_json::from_str function. There is also from_slice for parsing from a byte slice &[u8] and from_reader for parsing from any io::Read like a File or a TCP stream.

use serde_json::{Result, Value};

fn untyped_example() -> Result<()> {
    // Some JSON input data as a &str. Maybe this comes from the user.
    let data = r#"
        {
            "name": "John Doe",
            "age": 43,
            "phones": [
                "+44 1234567",
                "+44 2345678"
            ]
        }"#;

    // Parse the string of data into serde_json::Value.
    let v: Value = serde_json::from_str(data)?;

    // Access parts of the data by indexing with square brackets.
    println!("Please call {} at the number {}", v["name"], v["phones"][0]);

    Ok(())
}

The result of square bracket indexing like v["name"] is a borrow of the data at that index, so the type is &Value. A JSON map can be indexed with string keys, while a JSON array can be indexed with integer keys. If the type of the data is not right for the type with which it is being indexed, or if a map does not contain the key being indexed, or if the index into a vector is out of bounds, the returned element is Value::Null.

When a Value is printed, it is printed as a JSON string. So in the code above, the output looks like Please call "John Doe" at the number "+44 1234567". The quotation marks appear because v["name"] is a &Value containing a JSON string and its JSON representation is "John Doe". Printing as a plain string without quotation marks involves converting from a JSON string to a Rust string with as_str() or avoiding the use of Value as described in the following section.

The Value representation is sufficient for very basic tasks but can be tedious to work with for anything more significant. Error handling is verbose to implement correctly, for example imagine trying to detect the presence of unrecognized fields in the input data. The compiler is powerless to help you when you make a mistake, for example imagine typoing v["name"] as v["nmae"] in one of the dozens of places it is used in your code.

Parsing JSON as strongly typed data structures

Serde provides a powerful way of mapping JSON data into Rust data structures largely automatically.

use serde::{Deserialize, Serialize};
use serde_json::Result;

#[derive(Serialize, Deserialize)]
struct Person {
    name: String,
    age: u8,
    phones: Vec<String>,
}

fn typed_example() -> Result<()> {
    // Some JSON input data as a &str. Maybe this comes from the user.
    let data = r#"
        {
            "name": "John Doe",
            "age": 43,
            "phones": [
                "+44 1234567",
                "+44 2345678"
            ]
        }"#;

    // Parse the string of data into a Person object. This is exactly the
    // same function as the one that produced serde_json::Value above, but
    // now we are asking it for a Person as output.
    let p: Person = serde_json::from_str(data)?;

    // Do things just like with any other Rust data structure.
    println!("Please call {} at the number {}", p.name, p.phones[0]);

    Ok(())
}

This is the same serde_json::from_str function as before, but this time we assign the return value to a variable of type Person so Serde will automatically interpret the input data as a Person and produce informative error messages if the layout does not conform to what a Person is expected to look like.

Any type that implements Serde's Deserialize trait can be deserialized this way. This includes built-in Rust standard library types like Vec<T> and HashMap<K, V>, as well as any structs or enums annotated with #[derive(Deserialize)].

Once we have p of type Person, our IDE and the Rust compiler can help us use it correctly like they do for any other Rust code. The IDE can autocomplete field names to prevent typos, which was impossible in the serde_json::Value representation. And the Rust compiler can check that when we write p.phones[0], then p.phones is guaranteed to be a Vec<String> so indexing into it makes sense and produces a String.

The necessary setup for using Serde's derive macros is explained on the Using derive page of the Serde site.

Constructing JSON values

Serde JSON provides a json! macro to build serde_json::Value objects with very natural JSON syntax.

use serde_json::json;

fn main() {
    // The type of `john` is `serde_json::Value`
    let john = json!({
        "name": "John Doe",
        "age": 43,
        "phones": [
            "+44 1234567",
            "+44 2345678"
        ]
    });

    println!("first phone number: {}", john["phones"][0]);

    // Convert to a string of JSON and print it out
    println!("{}", john.to_string());
}

The Value::to_string() function converts a serde_json::Value into a String of JSON text.

One neat thing about the json! macro is that variables and expressions can be interpolated directly into the JSON value as you are building it. Serde will check at compile time that the value you are interpolating is able to be represented as JSON.

let full_name = "John Doe";
let age_last_year = 42;

// The type of `john` is `serde_json::Value`
let john = json!({
    "name": full_name,
    "age": age_last_year + 1,
    "phones": [
        format!("+44 {}", random_phone())
    ]
});

This is amazingly convenient, but we have the problem we had before with Value: the IDE and Rust compiler cannot help us if we get it wrong. Serde JSON provides a better way of serializing strongly-typed data structures into JSON text.

Creating JSON by serializing data structures

A data structure can be converted to a JSON string by serde_json::to_string. There is also serde_json::to_vec which serializes to a Vec<u8> and serde_json::to_writer which serializes to any io::Write such as a File or a TCP stream.

use serde::{Deserialize, Serialize};
use serde_json::Result;

#[derive(Serialize, Deserialize)]
struct Address {
    street: String,
    city: String,
}

fn print_an_address() -> Result<()> {
    // Some data structure.
    let address = Address {
        street: "10 Downing Street".to_owned(),
        city: "London".to_owned(),
    };

    // Serialize it to a JSON string.
    let j = serde_json::to_string(&address)?;

    // Print, write to a file, or send to an HTTP server.
    println!("{}", j);

    Ok(())
}

Any type that implements Serde's Serialize trait can be serialized this way. This includes built-in Rust standard library types like Vec<T> and HashMap<K, V>, as well as any structs or enums annotated with #[derive(Serialize)].

Performance

It is fast. You should expect in the ballpark of 500 to 1000 megabytes per second deserialization and 600 to 900 megabytes per second serialization, depending on the characteristics of your data. This is competitive with the fastest C and C++ JSON libraries or even 30% faster for many use cases. Benchmarks live in the serde-rs/json-benchmark repo.

Getting help

Serde is one of the most widely used Rust libraries, so any place that Rustaceans congregate will be able to help you out. For chat, consider trying the #rust-questions or #rust-beginners channels of the unofficial community Discord (invite: https://discord.gg/rust-lang-community), the #rust-usage or #beginners channels of the official Rust Project Discord (invite: https://discord.gg/rust-lang), or the #general stream in Zulip. For asynchronous, consider the [rust] tag on StackOverflow, the /r/rust subreddit which has a pinned weekly easy questions post, or the Rust Discourse forum. It's acceptable to file a support issue in this repo, but they tend not to get as many eyes as any of the above and may get closed without a response after some time.

No-std support

As long as there is a memory allocator, it is possible to use serde_json without the rest of the Rust standard library. This is supported on Rust 1.36+. Disable the default "std" feature and enable the "alloc" feature:

[dependencies]
serde_json = { version = "1.0", default-features = false, features = ["alloc"] }

For JSON support in Serde without a memory allocator, please see the serde-json-core crate.

Link: https://crates.io/crates/serde_json

#rust  #rustlang  #encode   #json