Derive Macro AsVariantMut

#[derive(AsVariantMut)]
{
    // Attributes available to this derive:
    #[enumcapsulate]
}

Derive macro generating an impl of the trait From<T>.

It generates an impl for each of the enum’s newtype variants, where Inner is the variant’s field type and Outer is the enclosing enum’s type.

struct Inner;

enum Outer {
    Inner(Inner),
    // ...
}

// The generated impls look something along these lines:

impl AsVariantMut<Inner> for Outer {
    fn as_variant_mut(&mut self) -> Option<&mut Inner> {
        match self {
            Outer::Inner(inner) => Some(inner),
            _ => None,
        }
    }
}

// ...