Command Line Applications in Rust

Rust is a statically compiled, fast language with great tooling and a rapidly growing ecosystem. That makes it a great fit for writing command line applications: They should be small, portable, and quick to run. Command line applications are also a great way to get started with learning Rust; or to introduce Rust to your team!

• 整理自 Command line apps in Rust

重点提示

Arguments

C 语言的 CLI 程序处理参数的逻辑是过程式的，即每次执行都会通过 argv 来获取本次执行的参数并进行相应的处理 (Rust 的 std::env::args() 处理 CLI 程序的参数方式也类似，都是对每次执行实例进行过程式的处理)，而 Clap 不同，它类似于面向对象的思想，通过定义一个结构体 (object)，每次运行时通过 clap::Parser::parse 获取并处理本次运行的参数 (即实例化 object)，这样开发的 CLI 程序扩展性会更好。

BufReader

Struct std::io::BufReader 中关于系统调用 (syscall) 的开销，以及如何使用 buffer 这一机制减少 syscall 调用以此提高效能，进行了比较直观的描述:

It can be excessively inefficient to work directly with a Read instance. For example, every call to read on TcpStream results in a system call. A BufReader performs large, infrequent reads on the underlying Read and maintains an in-memory buffer of the results.

BufReader can improve the speed of programs that make small and repeated read calls to the same file or network socket. It does not help when reading very large amounts at once, or reading just one or a few times. It also provides no advantage when reading from a source that is already in memory, like a Vec.

When the BufReader is dropped, the contents of its buffer will be discarded. Creating multiple instances of a BufReader on the same stream can cause data loss. Reading from the underlying reader after unwrapping the BufReader with BufReader::into_inner can also cause data loss.

Documentations

这里列举视频中一些概念相关的 documentation

学习的一手资料是官方文档，请务必自主学会阅读规格书之类的资料

Crate std

可以使用这里提供的搜素栏进行搜索 (BTW 不要浪费时间在 Google 搜寻上！)

• Function std::fs::read_to_string
• Function std::env::args
• Struct std::path::PathBuf
• Struct std::io::BufReader
• method std::iter::Iterator::nth

Primitive Type str:

• method str::lines
• method str::contains

expect:

• method std::option::Option::expect
• method std::result::Result::expect

Crate clap

• method clap::Parser::parse

References