Strum

Strum is a set of macros and traits for working with enums and strings easier in Rust.

Compatibility

Strum is currently compatible with versions of rustc >= 1.56.1. Pull Requests that improve compatibility with older versions are welcome. The project goal is to support a rust version for at least 2 years after release and even longer is preferred since this project changes slowly.

Including Strum in Your Project

Import strum and strum_macros into your project by adding the following lines to your Cargo.toml. Strum_macros contains the macros needed to derive all the traits in Strum.

[dependencies]
strum = "0.26"
strum_macros = "0.26"

# You can also use the "derive" feature, and import the macros directly from "strum"
# strum = { version = "0.26", features = ["derive"] }

Strum Macros

Strum has implemented the following macros:

Macro	Description
EnumString	Converts strings to enum variants based on their name.
Display	Converts enum variants to strings
FromRepr	Convert from an integer to an enum.
AsRefStr	Implement AsRef<str> for MyEnum
IntoStaticStr	Implements From<MyEnum> for &'static str on an enum
EnumIter	Creates a new type that iterates of the variants of an enum.
EnumProperty	Add custom properties to enum variants.
EnumMessage	Add a verbose message to an enum variant.
EnumDiscriminants	Generate a new type with only the discriminant names.
EnumCount	Add a constant usize equal to the number of variants.
VariantArray	Adds an associated VARIANTS constant which is an array of all enum discriminants
VariantNames	Adds an associated VARIANTS constant which is an array of discriminant names
EnumTable	Experimental, creates a new type that stores an item of a specified type for each variant of the enum.

Contributing

Thanks for your interest in contributing. Bug fixes are always welcome. If you are interested in implementing or adding a macro, please open an issue first to discuss the feature. I have limited bandwidth to review new features.

The project is divided into 3 parts, the traits are in the /strum folder. The procedural macros are in the /strum_macros folder, and the integration tests are in /strum_tests. If you are adding additional features to strum or strum_macros, you should make sure to run the tests and add new integration tests to make sure the features work as expected.

Debugging

To see the generated code, set the STRUM_DEBUG environment variable before compiling your code. STRUM_DEBUG=1 will dump all of the generated code for every type. STRUM_DEBUG=YourType will only dump the code generated on a type named YourType.

Name

Strum is short for STRing enUM because it's a library for augmenting enums with additional information through strings.

Strumming is also a very whimsical motion, much like writing Rust code.

Fork Information

We're using a fork of strum from PR #353 which adds the const_into_str feature. This feature enables const evaluation of enum-to-string conversions, allowing us to use enum string representations in const contexts.

Example usage:

#[derive(IntoStaticStr)]
#[strum(const_into_str)]
enum Color {
    Red,
    Blue,
    #[strum(serialize = "dark_green")]
    Green,
}

// Can be used in const contexts
const RED_STR: &'static str = Color::Red.into_str();  // "Red"
const GREEN_STR: &'static str = Color::Green.into_str();  // "dark_green"