#enum #macro #pro-macro

macro enum_cycling_derive

Small macro for working with enums

2 unstable releases

0.2.0 Jan 14, 2022
0.1.0 Mar 5, 2021

#1880 in Procedural macros

30 downloads per month
Used in enum_cycling

MIT license

7KB
154 lines

Enum Cycling

Enum Cycling is just a single macro that aims to make working with enums easier in Rust.

Including in a Project

Import enum_cycling into your project by adding this line to your Cargo.toml.

[dependencies]
enum_cycling = "0.1.0"
enum_cycling_derive = "0.1.0"

# You can also just use the "derive" feature
# enum_cycling = { version = "0.1.0", features = ["derive"]}

Enum Cycling Macros

Enum Cycling has implemented these macros:

Macro Description
EnumCycle Adds two methods .up() and .down() to go from one enum variant to the one either above or below it.

How to Use:

EnumCycle

This derive was originally written while I was in the proccess of developing a game, and was working on the internal menus. I got really tired of having to write the matches by hand, and as such spent way longer learning how, and writing a macro to do the work for me.

use enum_cycling::EnumCycle;

#[derive(EnumCycle)]
pub enum Menu {
    Main,
    Settings,
    Quit,

    #[skip]
    Secret,
}

// KeyCode is not defined within the crate. It is used to demonstrate a use case for EnumCycle
pub fn current_menu(menu: Menu, player_input: KeyCode) -> Menu {
    match player_input {
        KeyCode::W => menu.up(),
        KeyCode::S => menu.down(),
        _ => menu,
    }
}

However, lets say that you don't want to have to worry about how your enum is sorted, or maybe you would like to keep it sorted alphabetically, and would still like to use EnumCycle. In this case, you may be a fan of using the 'cycle' attribute!

use enum_cycling::EnumCycle;

#[derive(EnumCycle)]
#[cycle(Main, Settings, Quit)]
pub enum Menu {
    Main,
    Quit,
    Secret,
    Settings,
}

pub fn current_menu(menu: Menu, player_input: KeyCode) -> Menu {
    match player_input {
        KeyCode::W => menu.up(),
        KeyCode::S => menu.down(),
        _ => menu,
    }
}

Both of these examples run exactly the same, and result in the same generated code!

Dependencies

~210–610KB
~15K SLoC