从输入中的任何地方解析 Structopt 标志

Question

我希望能够在我的命令行工具中使用 'universal' 标志，它使用 StructOpt。也就是说，如果我有一个标志（例如 --debug），我希望它的行为相同，而不管该标志在输入中的什么位置：

$ mycli --debug alpha
$ mycli alpha --debug

（alpha 和 --debug 在此示例中只是有用的占位符；实际的子命令和标志会有所不同。）

实际行为：

$ cargo run -- --debug alpha                                                                                               nford 14:36:32
    Finished dev [unoptimized + debuginfo] target(s) in 0.01s
     Running `target/debug/scratch-rust --debug alpha`
Debug mode enabled!
Alpha subcommand selected.
$ cargo run -- alpha --debug                                                                                               nford 14:36:27
    Finished dev [unoptimized + debuginfo] target(s) in 0.01s
     Running `target/debug/scratch-rust alpha --debug`
error: Found argument '--debug' which wasn't expected, or isn't valid in this context

USAGE:
    scratch-rust alpha

预期行为：

$ cargo run -- --debug alpha                                                                                               nford 14:36:32
    Finished dev [unoptimized + debuginfo] target(s) in 0.01s
     Running `target/debug/scratch-rust --debug alpha`
Debug mode enabled!
Alpha subcommand selected.
$ cargo run -- alpha --debug       
    Finished dev [unoptimized + debuginfo] target(s) in 0.01s
     Running `target/debug/scratch-rust --debug alpha`
Debug mode enabled!
Alpha subcommand selected.

这是我的 main.rs 代码：

use std::str::FromStr;
use structopt::StructOpt;
use std::io::{Error, ErrorKind};

#[derive(Debug, StructOpt)]
/// Specific task being executed; one task might imply others, depending on flags.
pub enum Subcommand {
    Alpha,
    Omega,
}

impl FromStr for Subcommand {
    type Err = Error;
    fn from_str(subcommand_input: &str) -> Result<Self, Self::Err> {
        match subcommand_input {
            "alpha" => Ok(Subcommand::Alpha),
            "omega" => Ok(Subcommand::Omega),
            _ => Err(Error::new(ErrorKind::Other, "Unrecognized subcommand.")),
        }
    }
}

#[derive(Debug, StructOpt)]
#[structopt(
    name = "Minimal Example CLI",
    about = "A minimal example of multi-location command line inputs.",
)]
pub struct CLIOpts {
    /// Set logging to verbose mode.
    // short and long flags (-d, --debug) will be deduced from the field's name
    #[structopt(short, long)]
    pub debug: bool,

    #[structopt(subcommand)]
    pub cmd: Subcommand,
}


fn main() {
    let args = CLIOpts::from_args();
    if args.debug {
        println!("Debug mode enabled!");
    }
    match args.cmd {
        Subcommand::Alpha => println!("Alpha subcommand selected."),
        Subcommand::Omega => println!("Omega subcommand selected."),
    }
}

这是我的 Cargo.toml 文件（上面的例子不会工作 w/o structopt 依赖）：

[package]
name = "scratch-rust"
version = "0.1.0"
edition = "2018"

[dependencies]
structopt = "*"

有没有一种方法可以做到这一点而无需在子命令的每个级别复制 'universal' 标志？

Answer 1

Clap 有 global() method for arguments that does what you want. You can access this method vis Structopt using raw attributes:

pub struct CLIOpts {
    /// Set logging to verbose mode.
    // short and long flags (-d, --debug) will be deduced from the field's name
    #[structopt(short, long, global = true)]
    pub debug: bool,

    #[structopt(subcommand)]
    pub cmd: Subcommand,
}

（注意为 debug 添加的 global 属性）

应用程序现在可以按照您希望的方式运行：

$ cargo run -- --debug alpha
    Finished dev [unoptimized + debuginfo] target(s) in 0.02s
     Running `target/debug/scratch-rust --debug alpha`
Debug mode enabled!
Alpha subcommand selected.
$ cargo run -- alpha --debug
    Finished dev [unoptimized + debuginfo] target(s) in 0.02s
     Running `target/debug/scratch-rust alpha --debug`
Debug mode enabled!
Alpha subcommand selected.

从输入中的任何地方解析 Structopt 标志

Parse Structopt flag from anywhere in the input

rust

structopt