//! # Documentation for Additional Attributes
//!
//! Strum supports several custom attributes to modify the generated code. At the enum level, the
//! `#[strum(serialize_all = "snake_case")]` attribute can be used to change the case used when
//! serializing to and deserializing from strings:
//!
//! ```rust
//! use std::string::ToString;
//! use strum;
//! use strum_macros;
//!
//! #[derive(Debug, Eq, PartialEq, strum_macros::ToString)]
//! #[strum(serialize_all = "snake_case")]
//! enum Brightness {
//!     DarkBlack,
//!     Dim {
//!         glow: usize,
//!     },
//!     #[strum(serialize = "bright")]
//!     BrightWhite,
//! }
//!
//! assert_eq!(
//!     String::from("dark_black"),
//!     Brightness::DarkBlack.to_string().as_ref()
//! );
//! assert_eq!(
//!     String::from("dim"),
//!     Brightness::Dim { glow: 0 }.to_string().as_ref()
//! );
//! assert_eq!(
//!     String::from("bright"),
//!     Brightness::BrightWhite.to_string().as_ref()
//! );
//! ```
//!
//! Custom attributes are applied to a variant by adding `#[strum(parameter="value")]` to the variant.
//!
//! - `serialize="..."`: Changes the text that `FromStr()` looks for when parsing a string. This attribute can
//!    be applied multiple times to an element and the enum variant will be parsed if any of them match.
//!
//! - `to_string="..."`: Similar to `serialize`. This value will be included when using `FromStr()`. More importantly,
//!    this specifies what text to use when calling `variant.to_string()` with the `ToString` derivation, or when calling `variant.as_ref()` with `AsRefStr`.
//!
//! - `default`: Applied to a single variant of an enum. The variant must be a Tuple-like
//!    variant with a single piece of data that can be create from a `&str` i.e. `T: From<&str>`.
//!    The generated code will now return the variant with the input string captured as shown below
//!    instead of failing.
//!
//!     ```rust,ignore
//!     // Replaces this:
//!     _ => Err(strum::ParseError::VariantNotFound)
//!     // With this in generated code:
//!     default => Ok(Variant(default.into()))
//!     ```
//!     The plugin will fail if the data doesn't implement From<&str>. You can only have one `default`
//!     on your enum.
//!
//! - `disabled`: removes variant from generated code.
//!
//! - `message=".."`: Adds a message to enum variant. This is used in conjunction with the `EnumMessage`
//!    trait to associate a message with a variant. If `detailed_message` is not provided,
//!    then `message` will also be returned when get_detailed_message() is called.
//!
//! - `detailed_message=".."`: Adds a more detailed message to a variant. If this value is omitted, then
//!    `message` will be used in it's place.
//!
//! - `props(key="value")`: Enables associating additional information with a given variant.