`Enable<T>` is a wrapper that adds one extra field `enabled` when the `T`
is serialized with `Serde`. That field can be `true`, in which case all
of the fields for `T` need to be present, or it can be `false` at which point
all fields of `T` can be ommited.
The use case is for configuration YAMLs where sections can be toggled on or off.
```
use serde::{Deserialize, Serialize};
use serde_enabled::Enable;
#[derive(Deserialize, Serialize, Debug, PartialEq, Eq)]
struct Outside {
inside: Enable<Inside>,
}
#[derive(Deserialize, Serialize, Debug, PartialEq, Eq)]
struct Inside {
thing: u32,
other: String,
}
let raw = indoc::indoc! {r#"
inside:
enable: false
thing: 1
other: "Great"
"#};
let o: Outside = serde_yaml::from_str(raw).unwrap();
assert!(!o.inside.is_enabled());
let raw = indoc::indoc! {r#"
inside:
enable: true
thing: 1
other: "Great"
"#};
let o: Outside = serde_yaml::from_str(raw).unwrap();
assert!(o.inside.is_enabled());
assert_eq!(
o,
Outside {
inside: Enable::On(Inside {
thing: 1,
other: "Great".into()
})
}
);
```