Rust Traits, what are they?
This concept is interesting and I wanted to write it down as I learned it. I’ve just started learing Rust and will have the terminology wrong!
Traits can be added to types to allow them to do something, as if these were classes in C++ that already had methods implemented.
In this scenario, I’m imagining that it’s very importand to check if a number is divisible by seven, and if it actually is the number seven. I can add a function to the “i32” and “u32” object. I would probably need to do this to i64 too, but this isn’t particularly exciting to reiterate in code below.
trait Sevens {
fn divisible_by_seven(&self) -> bool ;
fn is_seven(&self) -> bool ;
}
impl Sevens for i32 {
fn divisible_by_seven(&self) -> bool{
self%7 == 0
}
fn is_seven(&self) -> bool{
7 == *self
}
}
And if I want the same to work on u32, I can add this to the code:
impl Sevens for u32 {
fn divisible_by_seven(&self) -> bool{
self%7 == 0
}
fn is_seven(&self) -> bool{
7 == *self
}
}
And then main can be added (note, these are all in the same file at the moment as I haven’t imported another file with a “use” declaration.
fn main() {
let x: i32 = 9;
let y: u32 = 49;
println!("Is {} divisible by 7? {}", x, x.divisible_by_seven());
println!("Is {} divisible by 7? {}", y, y.divisible_by_seven());
println!("Is {} equal to 7? {}", y, y.is_seven());
println!("Is {} equal to 7? {}", 7, 7.is_seven());
}
Ooh, notice I can now do 7.is_seven(), isn’t that interesting.