type-utilities-rs

Rust 中的类型工具。

省略

创建一个新的 Struct，省略指定的字段

use type_utilities_rs::omit;

// Create a new struct `NewS` with omitted field `b`
#[omit(NewS, [b])]
struct S {
    a: i32,
    b: &str,
}
// `NewS` will only have field `a`
let _ = NewS { a: 1 };

当未指定字段时，它将与原始结构相同

use type_utilities_rs::omit;

#[omit(NewS)]
struct S<'a> {
    a: i32,
    b: &'a str,
}
// `NewS` is same as the original struct `S`
let _ = NewS { a: 1, b: "hello" };

选择

创建一个新的 Struct，选择指定的字段

use type_utilities_rs::pick;

// Create a new struct `NewS` with picked field `b`
#[pick(NewS, [b])]
struct S<'a> {
   a: i32,
   b: &'a str,
   c: f64,
}

// `NewS` will only have field `b`
let _ = NewS { b: "hello" };

当未指定字段时，它将是空的 Struct

use type_utilities_rs::pick;

#[pick(NewS)]
struct S {
  a: i32,
  b: f64,
}

// `NewS` will be empty struct
let _ = NewS {};

部分

将所有字段更改为 Option 类型

use type_utilities_rs::partial;

// Create a new struct `NewS` with all fields optional
#[partial(NewS)]
struct S<'a> {
  a: i32,
  b: &'a str,
  c: f64,
}

// `NewS` will have all fields optional
let _ = NewS { a: Some(1), b: Some("hello"), c: Some(1.5) };

当字段已经是 Option 时，没有效果

use type_utilities_rs::partial;

#[partial(NewS)]
struct S {
 a: i32,
 b: Option<f64>,
}

let _ = NewS { a: Some(1), b: Some(1.1) };

必需

从 Option 类型中解包所有字段

use type_utilities_rs::required;

// Create a new struct `NewS` with all fields optional
#[required(NewS)]
struct S<'a> {
  a: Option<i32>,
  b: Option<&'a str>,
  c: f64,
}

// `NewS` will have all fields.
// When the field is not [`Option`], it's no effect
let _ = NewS { a: 1, b: "hello", c: 1.5 };