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d840d5650e
Before #2005, `Clap` was a special trait that derived all clap traits it detected were relevant (including an enum getting both `ArgEnum`, `Clap`, and `Subcommand`). Now, we have elevated `Clap`, `Args`, `Subcommand`, and `ArgEnum` to be user facing but the name `Clap` isn't very descriptive. This also helps further clarify the relationships so a crate providing an item to be `#[clap(flatten)]` or `#[clap(subcommand)]` is more likely to choose the needed trait to derive. Also, my proposed fix fo #2785 includes making `App` attributes almost exclusively for `Clap`. Clarifying the names/roles will help communicate this. For prior discussion, see #2583
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1.2 KiB
+++ title = "Fast & Modern CLI Framework for Rust" +++
Clap is a simple-to-use, efficient, and full-featured library for parsing command line arguments and subcommands when writing console/terminal applications.
Here is an example of a simple program:
use clap::Parser;
/// Simple program to greet a person
#[derive(Parser, Debug)]
#[clap(name = "hello")]
struct Hello {
/// Name of the person to greet
#[clap(short, long)]
name: String,
/// Number of times to greet
#[clap(short, long, default_value = "1")]
count: u8,
}
fn main() {
let hello = Hello::parse();
for _ in 0..hello.count {
println!("Hello {}!", hello.name)
}
}
The above example program can be run as shown below:
$ hello --name John --count 3
Hello John!
Hello John!
Hello John!
The program also has automatically generated help message:
hello
Simple program to greet a person
USAGE:
hello [OPTIONS] --name <name>
FLAGS:
-h, --help Print help information
-V, --version Print version information
OPTIONS:
-c, --count <count> Number of times to greet [default: 1]
-n, --name <name> Name of the person to greet