Rust Builder Pattern Example

rust-patterns-builder.rs

// Rust Builder Pattern Example

struct Foo { 
    x: i32,
    y: i32,
    z: i32
}

struct FooBuilder {
    x: i32,
    y: i32,
    z: i32
}

impl FooBuilder {
    
    fn new() -> FooBuilder {
        FooBuilder { x: 0, y: 0, z: 0 }
    }

    fn set_x<'a>(&'a mut self, x: i32) -> &'a mut FooBuilder {
        self.x = x;
        self
    }

    fn set_y<'a>(&'a mut self, y: i32) -> &'a mut FooBuilder {
        self.y = y;
        self
    }

    fn set_z<'a>(&'a mut self, z: i32) -> &'a mut FooBuilder {
        self.z = z;
        self
    }

    // ... lots of setters

    fn build(&self) -> Foo {
        Foo {x: self.x, y: self.y, z: self.z}
    }
}

fn main() {
    let foo = FooBuilder::new().set_x(1).set_y(2).set_z(3).build();
    println!("x: {}, y: {}, z: {}", foo.x, foo.y, foo.z);
}