精简构造器

pub struct Shape {  position: Vec3,  geometry: Geometry,  material: Option<Material>,}
impl Shape {  pub fn new(geometry: Geometry) -> Shape {    Shape {      position: Vec3::default(),      geometry,      material: None,    }  }
  pub fn with_position(mut self, position: Vec3) -> Shape {    self.position = position;    self  }
  pub fn with_material(mut self, material: Material) -> Shape {    self.material = Some(material);    self  }}
// Call site
let shape = Shape::new(Geometry::Sphere::with_radius(1))  .with_position(Vec3(0, 9, 2))  .with_material(Material::SolidColor(Color::Red));

pub struct Shape {  position: Vec3,  geometry: Geometry,  material: Option<Material>,}
pub struct ShapeBuilder {  position: Option<Vec3>,  geometry: Option<Geometry>,  texture: Option<Texture>,}
impl Shape {  pub fn builder() -> ShapeBuilder { ... }}
impl ShapeBuilder {  pub fn position(&mut self, position: Vec3) -> &mut Self { ... }  pub fn geometry(&mut self, geometry: Geometry) -> &mut Self { ... }  pub fn material(&mut self, material: Material) -> &mut Self { ... }  pub fn build(&self) -> Shape { ... }}
// Call site
let shape = Shape::builder()  .position(Vec3(9, 2))  .geometry(Geometry::Sphere::with_radius(1))  .material(Material::SolidColor(Color::Red))  .build();

impl PeerManagerActor {  pub fn new(    store: Store,    config: NetworkConfig,    client_addr: Recipient<NetworkClientMessages>,    view_client_addr: Recipient<NetworkViewClientMessages>,    routing_table_addr: Addr<RoutingTableActor>,  ) -> anyhow::Result<Self> {

pub fn new(    store: Store,    config: NetworkConfig,    client_addr: Recipient<NetworkClientMessages>,    view_client_addr: Recipient<NetworkViewClientMessages>,    routing_table_addr: Addr<RoutingTableActor>,+   ping_counter: Box<dyn PingCounter>,  ) -> anyhow::Result<Self> {

pub fn fancy(mut self) -> Self {  self.with_fancy(true)}
pub fn with_fancy(mut self, yes: bool) -> Self {  self.fancy = yes;  self}