Command Line Argument Parser for Rust
Dual-licensed under Apache 2.0 or MIT.
Create your command-line parser, with all of the bells and whistles, declaratively or procedurally.
This uses our
Derive API
which provides access to the Builder API as attributes on a struct:
```rust,no_run use clap::Parser;
/// Simple program to greet a person
struct Args { /// Name of the person to greet #[clap(short, long)] name: String,
/// Number of times to greet
#[clap(short, long, default_value_t = 1)]
count: u8,
}
fn main() { let args = Args::parse();
for _ in 0..args.count {
println!("Hello {}!", args.name)
}
}
Add this to `Cargo.toml`:
toml
[dependencies]
clap = { version = "3.1.9", features = ["derive"] }
bash
$ demo --help
clap [..]
Simple program to greet a person
USAGE:
demo[EXE] [OPTIONS] --name
OPTIONS:
-c, --count
*(version number and.exe` extension on windows replaced by placeholders)*
While these aspirations can be at odds with fast build times and low binary size, we will still strive to keep these reasonable for the flexibility you get. Check out the argparse-benchmarks for CLI parsers optimized for other use cases.
Why use the declarative Derive API: - Easier to read, write, and modify - Easier to keep the argument declaration and reading of argument in sync - Easier to reuse, e.g. clap-verbosity-flag
Why use the procedural Builder API: - Faster compile times if you aren't already using other procedural macros - More flexible, e.g. you can look up how many times an argument showed up, what its values were, and what were the indexes of those values. The Derive API can only report presence, number of occurrences, or values but no indices or combinations of data.
*) on Windows like you do LinuxCommand::long_versiontrycmd: Snapshot testing
assert_cmd and assert_fsno_std environments in a backwards compatible manner.Did you mean '--myoption'? feature for when users make typos.#[derive(Parser)]). Without this you must use one of the other methods of creating a clap CLI listed above.CARGO_* environment variables.Warning: These may contain breaking changes between minor releases.
Command::replaceCommand::multicallArgMatches::grouped_values_of
