310人参与 • 2024-08-15 • rust
这里参考资料2的文章，修改部分代码后如下。这段代码的目的是使用构建器模式创建和初始化person对象。以下是各部分的解释：
#[derive(debug)]
struct person {
name: string,
age: u32,
address: option<string>,
sex: option<string>,
}
struct personbuilder {
name: string,
age: u32,
address: option<string>,
sex: option<string>,
}
impl personbuilder {
fn new(name: string, age: u32) -> self {
self {
name,
age,
address: none,
sex: none,
}
}
fn with_address(mut self, address: string) -> self {
self.address = some(address);
self
}
fn with_sex(mut self, sex: string) -> self {
self.sex = some(sex);
self
}
fn build(self) -> person {
person {
name: self.name,
age: self.age,
address: self.address,
sex: self.sex,
}
}
}
fn main() {
let person = personbuilder::new("alice".to_string(), 30)
.with_address("wonderland".to_string())
.with_sex("female".to_string())
.build();
println!("{:?}", person);
// access the fields to demonstrate usage
println!("name: {}", person.name);
println!("age: {}", person.age);
if let some(address) = &person.address {
println!("address: {}", address);
} else {
println!("address: none");
}
if let some(sex) = &person.sex {
println!("sex: {}", sex);
} else {
println!("sex: none");
}
}person { name: "alice", age: 30, address: some("wonderland"), sex: some("female") }
name: alice
age: 30
address: wonderland
sex: female了解完rust如何实现构建器模式后，如果我们想要在实际项目中使用构建器，当然可以不用自己手动实现，可以使用第三方库bon，引入方式如下
cargo.toml
[dependencies] bon = "1.1.0"
use bon::bon;
#[derive(debug)]
struct person {
name: string,
age: u32,
address: option<string>,
sex: option<string>,
}
#[bon] // 使用 bon 库的宏
impl person {
#[builder]
fn new(name: string, age: u32) -> self {
self {
name,
age,
address: none,
sex: none,
}
}
#[builder]
fn with_address(&mut self, address: string) {
self.address = some(address);
}
#[builder]
fn with_sex(&mut self, sex: string) {
self.sex = some(sex);
}
}
fn main() {
let mut person = person::builder()
.name("alice".to_string())
.age(30)
.build();
person.with_address().address("wonderland").call();
person.with_sex().sex("female").call();
println!("{:?}", person);
println!("name: {}", person.name);
println!("age: {}", person.age);
if let some(address) = &person.address {
println!("address: {}", address);
} else {
println!("address: none");
}
if let some(sex) = &person.sex {
println!("sex: {}", sex);
} else {
println!("sex: none");
}
}person { name: "alice", age: 30, address: some("wonderland"), sex: some("female") }
name: alice
age: 30
address: wonderland
sex: female运行结果和手动实现方式一致。当然这种方式更为简洁，可以省略很多代码实现，容易维护和阅读，更推荐使用
参考资料3，bon除了结构体的构建器和关联方法的构建器，还有函数的构建器
fn main() {
#[bon::builder]
fn greet(name: &str, age: u32) -> string {
format!("hello {name} with age {age}!")
}
let greeting = greet()
.name("bon")
.age(24)
.call();
if greeting == "hello bon with age 24!" {
println!("assertion passed: {}", greeting);
} else {
println!("assertion failed");
}
}assertion passed: hello bon with age 24!
how to do named function arguments in rust
overview | bon (elastio.github.io)
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