CODEWITHSUNDEEP
enumsruststatic
James Parker
James Parker

Reputation: 477

Static Enum in Rust

Is it possible define an enum without worrying about memory allocation in Rust?

Suppose the following is the definition of my enum.

pub enum Orientation {
    North,
    South,
    East,
    West,
}

I would like to know whether it is possible to refer to the same instance of say Orientation::North in the code.

Does the following code produce two separate instances of North?

let o1 = Orientation::North;
let o2 = Orientation::North;

I know I can achieve it by defining static variables like below. Is there a better (syntactically safer/simpler/cleaner) way to do the same thing?

pub enum Orientation {
    North,
    South,
    East,
    West,
}

static NORTH: Orientation = Orientation::North;
static SOUTH: Orientation = Orientation::South;
static WEST: Orientation = Orientation::West;
static EAST: Orientation = Orientation::East;

Upvotes: 5

Views: 2979

Answers (1)

Peter Hall
Peter Hall

Reputation: 58735

The code you are asking about, at runtime, is identical to as if you had written:

let o1: u8 = 0;
let o2: u8 = 0;

Enums give you abstraction over what is really happening so you get efficiency and syntactic convenience at the same time, along with type-checking and errors when you forget a variant in a match.

Creating static "constants" won't achieve anything, because passing bytes around is about the fastest thing you could do already.

Is there a better (syntactically safer/simpler/cleaner) way to do the same thing?

The "best" way to use the enum is in exactly the simplest way possible:

let o1 = Orientation::North;
let o2 = Orientation::North;

Upvotes: 10

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