constructors
    |---------src
    |          |----------lib.rs
    |          |----------constructor_file.rs    
    |
    |----------Cargo.toml
    |----------main.rs

• • 库文件**

pub mod constructor_file;

• • 构造函数文件. rs**

pub struct Person {
    name: String,
    age: u32,
}

impl Person {
    pub fn new(name: String, age: u32) -> Person {
        Person { name, age }
    }
    pub fn show(self)
    {
        println!("Name: {}, Age: {}", self.name, self.age);
    }
}

• • 主文件. rs**

use constructor_lib::constructor_file::Person;

fn main() {
    let person = Person { name: "Alice".to_string(), age: 33 };
    person.show();
    let person2 = Person::new("Bob".to_string(), 99 );
    person2.show();
}

• • 货物运输工具**

[package]
name = "constructor_lib"
version = "0.1.0"
edition = "2021"

[[bin]]
name="constructor_exe"
path="main.rs"

上面的项目给我带来了以下生成错误

C:\git\Rust examples\constructors>cargo build
   Compiling constructor_lib v0.1.0 (C:\git\Rust examples\constructors)
error[E0451]: field `name` of struct `Person` is private
 --> main.rs:4:27
  |
4 |     let person = Person { name: "Alice".to_string(), age: 33 };
  |                           ^^^^^^^^^^^^^^^^^^^^^^^^^ private field

error[E0451]: field `age` of struct `Person` is private
 --> main.rs:4:54
  |
4 |     let person = Person { name: "Alice".to_string(), age: 33 };
  |                                                      ^^^^^^^ private field

For more information about this error, try `rustc --explain E0451`.
error: could not compile `constructor_lib` due to 2 previous errors

C:\git\Rust examples\constructors>

为什么当我把Person和main.rs保存在同一个文件中时，这个错误没有出现？

• • 主文件. rs**

//use constructor_lib::constructor_file::Person;
pub struct Person {
    name: String,
    age: u32,
}

impl Person {
    pub fn new(name: String, age: u32) -> Person {
        Person { name, age }
    }
    pub fn show(self)
    {
        println!("Name: {}, Age: {}", self.name, self.age);
    }
}

fn main() {
    let person = Person { name: "Alice".to_string(), age: 33 };
    person.show();
    let person2 = Person::new("Bob".to_string(), 99 );
    person2.show();
}