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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]