Nathan Ringo

我已经看到构建器模式主要是通过在修改时获得构建器的所有权来实现的,并且通过引用 build() 是的。例如,

#[derive(Debug, Eq, PartialEq)]
struct Foo {
    value: usize,
}

struct FooBuilder {
    foos: usize,
    bars: usize,
}

impl FooBuilder {
    fn new() -> FooBuilder {
        FooBuilder {
            foos: 0,
            bars: 0,
        }
    }
    fn set_foos(mut self, foos: usize) -> FooBuilder {
        self.foos = foos;
        self
    }
    fn set_bars(mut self, bars: usize) -> FooBuilder {
        self.bars = bars;
        self
    }
    fn build(&self) -> Foo {
        Foo {
            value: self.foos + self.bars,
        }
    }
}

fn main() {
    let foo = FooBuilder::new()
        .set_foos(2)
        .set_bars(3)
        .build();
    assert_eq!(foo, Foo { value: 5 });
}

Try on Rust Playground

这使得链接简单,同时允许重用生成器。