用 clap 做更复杂的参数解析
Picker 适合轻量级的参数提取，但当参数数量多、有复杂的校验规则、或者需要自动生成 `--help` 时，可以接入 [clap](https://crates.io/crates/clap)。 ## 开启 clap 特性 ```toml [dependencies.mingling] features = ["clap"] [dependencies.clap] version = "4" features = ["derive", "color"] ``` ## dispatcher_clap `#[dispatcher_clap]` 加在 `clap::Parser` 结构体上，自动生成 Dispatcher： ```rust // Features: ["clap"] // Dependencies: // clap = "4" @@@ use mingling::macros::dispatcher_clap; #[derive(Default, clap::Parser, Groupped)] #[dispatcher_clap("greet", CMDGreet, help = true, error = ErrorGreetParsed)] pub struct EntryGreet { #[clap(default_value = "World")] name: String, #[arg(short, long, default_value_t = 1)] repeat: i32, } #[renderer] fn render_greet(greet: EntryGreet) { let count = greet.repeat.max(0) as usize; r_print!("Hello, "); for _ in 0..count { r_print!("{} ", greet.name); } r_println!("!"); } #[renderer] fn render_greet_parse_failed(err: ErrorGreetParsed) { r_println!("{}", *err); } ``` ## 与 BasicProgramSetup 配合 如果需要 `--help` 支持，在 main 中注册 `BasicProgramSetup` 并设置 clap 帮助的输出模式： ```rust // Features: ["clap"] // Dependencies: // clap = "4" @@@use mingling::setup::BasicProgramSetup; @@@use mingling::macros::dispatcher_clap; @@@#[derive(Default, clap::Parser, Groupped)] @@@#[dispatcher_clap("greet", CMDGreet)] @@@pub struct EntryGreet { @@@ name: String, @@@} @@@#[renderer] @@@fn render_greet(greet: EntryGreet) { @@@ r_println!("Hello, {}!", greet.name); @@@} @@@ fn main() { let mut program = ThisProgram::new(); program.with_setup(BasicProgramSetup); program.stdout_setting.clap_help_print_behaviour = mingling::ClapHelpPrintBehaviour::WriteToRenderResult; program.with_dispatcher(CMDGreet); program.exec_and_exit(); } ``` 详见 [example-clap-binding](https://mingling-rs.github.io/mingling/docs/example-viewer.html?name=example-clap-binding)。Written by @Weicao-CatilGrass