rust feature h和 workspace相关知识 (十一)

feature 相关作用和描述

在 Rust 中，features（特性） 是一种控制可选功能和依赖的机制。它允许你在编译时根据不同的需求启用或禁用某些功能，优化构建，甚至改变代码的行为。Rust 的特性使得你可以轻松地为库提供不同的配置，或者在不同的环境中使用不同的功能

1.新建一个项目 study_feature_2025_1_23

Cargo.toml

[package]
name = "study_feature_2025_1_23"
version = "0.1.0"
edition = "2021"
publish = ["crates-io"]

[dependencies]
serde = {version = "1.0.217", features = ["derive"],optional = true}
rgb = {version = "0.8.43", features = ["serde"],optional = true}

[features]
color = ["dep:rgb"] # 依赖 rgb 项目 
shapes = ["color","dep:serde","rgb?/serde"] # 依赖加载 color,serde, 如果使用了 rgb 则加载 serde 特性
default = ["color"] # 默认开启 color feature

• lib.rs 代码如下

pub fn draw_line(x: i32, y: i32) {
    println!("Drawing a line at ({}, {})", x, y);
}

#[cfg(feature = "color")] // 这个是设置这个模块为一个feature : color 
pub mod color {
    pub use rgb::RGB;
    pub fn draw_line(x: i32,y: i32, color: &RGB<u16>){
        println!("{color}, Drawing a line at ({}, {})", x, y);
    }
}


#[cfg(feature = "shapes")] // 这个是设置这个模块为一个feature : shapes 
pub mod shapes {
    use serde::{Deserialize, Serialize};
    use rgb::RGB;
    
    #[derive(Debug,Serialize,Deserialize)]
    pub struct Rectangle {
        pub width: u32,
        pub height: u32,
        pub color: RGB<u16>,
    }

}

2.新建一个项目 study_feature_consumer_2025_1_23

Cargo.toml

[package]
name = "study_feature_consumer_2025_1_23"
version = "0.1.0"
edition = "2021"
publish = ["crates-io"]


[dependencies]
study_feature_2025_1_23 = {path = "../study_feature_2025_1_23",default-features = false,features = ["shapes"]}
# default-features  是false 关闭所有默认feature

• main.rs

use study_feature_2025_1_23::color;
use study_feature_2025_1_23::shapes;

fn main() {
    study_feature_2025_1_23::draw_line(1, 2);
    
    let color = color::RGB {
        r: 0,
        g: 0,
        b: 0,
    };
    
    color::draw_line(1, 2, &color);


    
    println!("形状: {:?}", shapes::Rectangle {
        width: 1,
        height: 2,
        color,
    });
}

workspace

[workspace]
resolver = "2"
members = [
    "hecto3_8",
    "hecto3_9",
    "hecto3_10",
    "hecto3_11",
    "hecto4_1",
    "hecto4_3",
    "hecto4_4",
    "hecto4_5",
    "hecto4_6",
    "hecto4_7",
    "hecto4_8",
    "hecto4_9",
    "hecto5_1",
    "hecto5_2",
    "hecto5_3",
    "hecto5_4",
    "hecto5_5",
    "hecto5_6",
    "hecto5_7",
    "hecto5_8",
    "hecto5_9",
    "hecto5_10",
    "hecto5_11",
]



[workspace.dependencies] # 依赖的全局包
env_logger = "0.11.3"


[profile.release]
lto = true
opt-level = "z"
panic = "abort"
# 编译器能进行全局优化
codegen-units = 1

[profile.dev]