Custom Attrs

A library that allows you to configure values specific to each variants of an enum.

Installation and Usage

Add this to your Cargo.toml file : toml [dependencies] custom_attrs = "1.2.2"

Attribute declaration.

By default, an attribute declaration is composed of two parts : the attribute's name and it's type.

```rust

[attr(name: u32)]

```

Optionally, you can add more components.

Optional components

You can set the visibility of the attribute. This will change the visibility of the getter function.

```rust

[attr(pub name: u32)]

enum Enum {} ```

By default, each attribute declared require a value to be set for each variant. If this requirement is not set, this library will produce an error.

You can disable this behavior by making it optional, by writing the type into an Option, or by adding a default value behind the attribute declaration. See the example below.

```rust

[attr(name: Option)]

enum Enum {} ```

```rust

[attr(name: u32 = 3)]

enum Enum {} ```

Setting a value

To set a value for a variant, just add the name of the attribute followed by the value you want to assign it.

rust enum Enum { #[attr(name = 4)] VariantA }

If the attribute is optional, you don't have to wrap you value into a Some. custom_attrs will do it for you. If you want the value to be None, just put None behind the value.

```rust enum Enum { #[attr(name = 4)] VariantA,

#[attr(name = None)]
VariantA,

} ```

Examples

```Rust use custom_attrs::CustomAttrs;

// ...

[derive(CustomAttrs)]

// set the attributes

[attr(pub a: usize)]

[attr(b: Option)] // attributes can be optional

[attr(c: &'static str = "Hello world!")] // and can also have default values

enum Enum { #[attr(a = 5)] #[attr(b = 3)] Variant1,

#[attr(a = 3)]
#[attr(c = "Hello again !")]
Variant2,

}

fn main() { let a = Enum::Variant1.get_a(); } ```

See the examples directory for more details.

License

Licensed under the MIT license.