1 unstable release
0.1.0 | Jun 25, 2019 |
---|
#205 in #options
11KB
166 lines
umbra
A macro to generate optional structs
Usage
Add the #[optional]
and #[nested]
attributes as follows:
use umbra::optional;
#[optional]
#[derive(Default)]
struct Foo {
id: u32,
name: String,
#[nested]
bar: Bar,
}
#[optional(derives = ["Debug"])]
#[derive(Default)]
struct Bar {
name: String,
value: Option<i32>,
}
The macro generates following structs:
#[derive(Default)]
struct Foo {
id: u32,
name: String,
bar: Bar,
}
#[derive(Default)]
struct Bar {
name: String,
value: Option<i32>,
}
struct OptionalFoo {
id: Option<u32>,
name: Option<String>,
bar: Option<OptionalBar>,
}
impl From<OptionalFoo> for Foo {
fn from(optional: OptionalFoo) -> Self {
let mut base = Self::default(); // create base values by default
if let Some(value) = optional.id {
base.id = value; // simple field
}
if let Some(value) = optional.bar {
base.bar = value.into(); // nested field
}
// ...
base
}
}
#[derive(Debug)]
struct OptionalBar {
name: Option<String>,
value: Option<i32>,
}
impl From<OptionalBar> for Bar {
fn from(optional: OptionalBar) -> Self {
let mut base = Self::default();
// ...
base
}
}
License
MIT
Dependencies
~230–670KB
~16K SLoC