Day 122 - Structs And Traits In Rust

A struct or structure is a custom Data Type that is a collection of related values that are put together to form a meaningful group. They are simillar to Object attributes as in Object Oriented Languages. Structs in Rust are simillar to how we define them in C and C++ but structs in Rust can do more than structs in C and C++.

Structs

To define a struct in Rust we use the struct keyword followed by the name of the struct and then {} and inside these we put the values that are related to the struct.

struct SuperHero {
    name: String,
    hero_name: String,
    age: u32,
    active: bool,
}

To use the struct we define a variable to which we will assign the struct with the name and age value inside the {} which we can later use in other places.

let bruce = SuperHero {
    name: String::from("Bruce"),
    hero_name: String::from("Batman"),
    age: 30,
    active: true,
};

We can use the dot notation to reference a property of the struct and can also use the dot notation to update the property of the Person.

bruce.name // Bruce
bruce.name = String::from("Bruce Wayne");
bruce.name // Bruce Wayne

But to allow the values of a struct to be updates later, the instance must be mutable.

let mut bruce = SuperHero {
    // ...
};

Creating Instaces With Values From Other Instances

We can also create instances from other inctances with sharing the values of other instances as well. For example:

let mut clark = SuperHero {
    name: String::from("Clark Kent"),
    hero_name: String::from("SuperMan"),
    ..bruce
};

Now clark will inherit the same values as the bruce except the ones we defined ourselves like name and hero_name. This show that clark is the same age as bruce and is also active.

Struct Methods

As said before that Rust structs are much more than the C and C++ becuase we can implement methods on the struct that we can call on the strcut to modify some value inside the instance of the struct. We implement a method by using impl keyword and after that the name of the struct on which we want to implement it and then inside the {} we define a new function with &self as the first argument which represents the instance itself just like the keyword self in Python and this in JavaScript.

impl Hero {
    fn say_my_name(&self) {
        println!("{}", slef.name)
    }
}

bruce.say_my_name() // Bruce Wayne

Tuple Struct

Rust also have Tuple Struct which we define the same way but without any name and {}.

struct RGB(i32, i32, i32);

let black = RGB(0, 0, 0);

We can reference a value of the tuple struct by using its index number with dor notation.

black.0 // 0
black.1 // 0
black.2 // 0

And that all for Struct. This one was a little simple for me to understand as I have worked with struct before in C while learning about Linked Lists and Hash Tables but still Rust struct are more powerful than they are in C and maybe some other languages.

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