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err_exit

A macro for exiting processes with formatted error messages.

Table of Contents

• Introduction
• Usage
• Design Philosophy
• A Little Story

Introduction

err_exit offers a macro to terminate the current process after printing a formatted error message to the standard error stream. This is designed for handling fatal errors in command-line applications where immediate termination is the intended action.

Usage

Incorporate err_exit into your project and utilize the macro as shown:

use err_exit::err_exit;

fn main() {
    let item = "file";
    err_exit!("Failed to read {}", item);
}

This code will output ❌ Failed to read file to stderr and then exit the process with a status code of 1.

Design Philosophy

The err_exit! macro is implemented using macro_rules!. It accepts format arguments, akin to eprintln!, directs the formatted string to standard error prefixed with a "❌" emoji, and subsequently calls std::process::exit(1) to halt the process.

This design provides a direct and explicit mechanism for handling unrecoverable errors, bypassing more complex error handling structures like Result and ? which are better suited for recoverable errors. The goal is to offer a clear and concise tool for situations where the program cannot and should not continue.

A Little Story

In the early days of computing, command-line utilities in Unix-like systems established a convention: exit with a status of 0 on success, and a non-zero value on failure. This allowed for the powerful composition of tools using shell scripts, where one program's failure could halt a chain of commands. Error messages were typically sent to a separate stream, stderr, to avoid polluting the standard output (stdout) intended for data.

Rust, a modern systems programming language, inherits these principles. While its Result enum and ? operator provide a robust system for handling errors that can be propagated and managed, not all errors are recoverable. For a command-line tool, a missing configuration file or a critical failed connection might be a point of no return.

The err_exit macro is a nod to this long-standing practice of immediate and clear termination. It encapsulates the "print-and-die" pattern into a reusable, idiomatic Rust macro. It's a simple tool for a simple, yet critical, task: stopping execution when there's nothing left to do but report failure. This approach, while seemingly basic, is a testament to a design philosophy that values clarity and predictability in failure scenarios.

err_exit

用于输出格式化错误信息并退出进程的宏。

目录

• 简介
• 使用
• 设计思路
• 相关故事

简介

err_exit 提供宏，可在标准错误流打印格式化错误信息后终止当前进程。该工具专为处理命令行应用中的致命错误而设计，适用于需要立即终止的场景。

使用

将 err_exit 集成到项目中，并如下使用宏：

use err_exit::err_exit;

fn main() {
    let item = "文件";
    err_exit!("读取{}失败", item);
}

此代码将向 stderr 输出 ❌ 读取文件失败，然后以状态码 1 退出进程。

设计思路

err_exit! 宏通过 macro_rules! 实现。它接受类似 eprintln! 的格式化参数，将带有 "❌" 表情符号前缀的格式化字符串定向到标准错误，随后调用 std::process::exit(1) 停止进程。

此设计为处理不可恢复错误提供了直接且明确的机制，绕过了更复杂的错误处理结构（如 Result 和 ?），后者更适用于可恢复错误。其目标是为程序无法也不应继续运行的情况，提供清晰简洁的工具。

相关故事

在计算早期，类 Unix 系统中的命令行工具建立了一个惯例：成功时以状态 0 退出，失败时以非零值退出。这允许通过 Shell 脚本对工具进行强大组合，其中一个程序的失败可以中止一连串命令。错误信息通常被发送到独立流 stderr，以避免污染用于数据的标准输出 stdout。

Rust 作为现代系统编程语言，继承了这些原则。虽然其 Result 枚举和 ? 运算符为处理可传播和可管理的错误提供了强大系统，但并非所有错误都是可恢复的。对于命令行工具，配置文件缺失或关键连接失败可能意味着无法挽回。

err_exit 宏正是对这种立即明确终止的悠久实践的致敬。它将“打印并退出”模式封装成可重用且符合 Rust 习惯的宏。这是一个用于简单但关键任务的简单工具：在除了报告失败之外无事可做时停止执行。这种方法看似基础，却证明了一种在失败场景中重视清晰性和可预见性的设计哲学。

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