m3tam3re.com/content/posts/rust-1.en.md

title, date, draft, series, tags

title	date	draft	series	tags
Part 1: Today we learn Rust	2020-09-18	false	Starting with rust	rust coding

I started working with the programming language Rust about 1 week ago. When I started programming again a year ago, I had shortlisted the languages to Go and Rust. Ultimately I decided to lear Go.

The reason why I'm stopping by Rust after a year is pure curiosity. I've heard a lot of good things about the language and it doesn't make you dumber either 😇.

should be feasible

I decided to do the whole thing as part of the challenge. Programming 1 hour a day is not that difficult for me now, I usually do that anyway. It remains to be seen whether I can consistently hold out fo.

Day 1 - Rust, Methods and Ownership

Like I said, I started Rust a week ago. I.e. I read the book (great to read by the way) and did the Rustlings course. Today I started to rewrite a small program in Rust. I learned a few things about ownership in Rust. I think this is best illustrated by the code:

use std::string::String;

#[derive(Debug)]
struct Person {
    name: String,
    age: i32,
}

impl Person {
    fn hello(self) {
        println!("Hello {}, your age is {}", self.name, self.age);
    }
}

fn main() {
    let bob = Person {
        name: String::from("Bob"),
        age: 32,
    };
    bob.hello();
    println!("{:?}", bob)
}

That looks right at first glance. If you let the program run you will get an error:

error[E0382]: borrow of moved value: `bob`
  --> src/main.rs:21:22
   |
16 |     let bob = Person {
   |         --- move occurs because `bob` has type `Person`, which does not implement the `Copy` trait
...
20 |     bob.hello();
   |         ------- `bob` moved due to this method call
21 |     println!("{:?}", bob)
   |                      ^^^ value borrowed here after move
   |
note: this function consumes the receiver `self` by taking ownership of it, which moves `bob`
  --> src/main.rs:10:14
   |
10 |     fn hello(self) {
   |   
     ^^^^

In Go you would initialize the person once and then use the methods as often as you like. Go would only differentiate between a pointer and a non-pointer receiver, but the function could still be used.

In Rust, using the method consumes the object, since it owns the object by using self.

Since I would like to use the person after using the method, I have to borrow this to the method:

// ...

impl Person {
    fn hello(&self) {
        println!("Hello" {}, your age is {}", self.name, self.age");
    }
}

//...

And everything works. After finishing the code block in the hello method, self is returned.

It will probably take me a little while to get used to it and stop at it one or two times.