pub trait Limit {
fn with_limit(self, limit: u32) -> Self;
fn limit(&self) -> Option<u32>;
}
macro_rules! impl_limit {
($name:path) => {
impl Limit for $name {
fn with_limit(mut self, limit: u32) -> $name {
self.limit = Some(limit);
self
}
fn limit(&self) -> Option<u32> {
self.limit
}
}
};
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn it_can_be_derived() {
struct Foo {
limit: Option<u32>,
}
impl_limit!(Foo);
let foo = Foo { limit: None };
let foo = foo.with_limit(7);
assert_eq!(foo.limit(), Some(7));
}
}