mirror of
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176 lines
7.8 KiB
Markdown
176 lines
7.8 KiB
Markdown
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# clap
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> **Command Line Argument Parser for Rust**
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[](https://crates.io/crates/clap)
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[](https://crates.io/crates/clap)
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[](https://github.com/clap-rs/clap/blob/v3.0.13/LICENSE-APACHE)
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[](https://github.com/clap-rs/clap/blob/v3.0.13/LICENSE-MIT)
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[](https://github.com/clap-rs/clap/actions/workflows/ci.yml?query=branch%3Astaging)
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[](https://coveralls.io/github/clap-rs/clap?branch=master)
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[](https://github.com/clap-rs/clap/graphs/contributors)
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Dual-licensed under [Apache 2.0](LICENSE-APACHE) or [MIT](LICENSE-MIT).
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1. [About](#about)
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2. Tutorial: [Builder API](https://github.com/clap-rs/clap/blob/v3.0.13/examples/tutorial_builder/README.md), [Derive API](https://github.com/clap-rs/clap/blob/v3.0.13/examples/tutorial_derive/README.md)
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3. [Examples](https://github.com/clap-rs/clap/blob/v3.0.13/examples/README.md)
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4. [API Reference](https://docs.rs/clap)
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- [Derive Reference](https://github.com/clap-rs/clap/blob/v3.0.13/examples/derive_ref/README.md)
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- [Feature Flags](#feature-flags)
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5. [CHANGELOG](https://github.com/clap-rs/clap/blob/v3.0.13/CHANGELOG.md)
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6. [FAQ](https://github.com/clap-rs/clap/blob/v3.0.13/docs/FAQ.md)
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7. [Questions & Discussions](https://github.com/clap-rs/clap/discussions)
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8. [Contributing](https://github.com/clap-rs/clap/blob/v3.0.13/CONTRIBUTING.md)
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8. [Sponsors](#sponsors)
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## About
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Create your command-line parser, with all of the bells and whistles, declaratively or procedurally.
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### Example
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This uses our
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[Derive API](https://github.com/clap-rs/clap/blob/v3.0.13/examples/tutorial_derive/README.md)
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which provides access to the [Builder API](https://github.com/clap-rs/clap/blob/v3.0.13/examples/tutorial_builder/README.md) as attributes on a `struct`:
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<!-- Copied from examples/demo.{rs,md} -->
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```rust,no_run
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use clap::Parser;
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/// Simple program to greet a person
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#[derive(Parser, Debug)]
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#[clap(author, version, about, long_about = None)]
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struct Args {
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/// Name of the person to greet
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#[clap(short, long)]
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name: String,
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/// Number of times to greet
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#[clap(short, long, default_value_t = 1)]
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count: u8,
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}
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fn main() {
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let args = Args::parse();
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for _ in 0..args.count {
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println!("Hello {}!", args.name)
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}
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}
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```
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Add this to `Cargo.toml`:
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```toml
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[dependencies]
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clap = { version = "3.0.13", features = ["derive"] }
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```
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```bash
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$ demo --help
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clap [..]
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A simple to use, efficient, and full-featured Command Line Argument Parser
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USAGE:
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demo[EXE] [OPTIONS] --name <NAME>
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OPTIONS:
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-c, --count <COUNT> Number of times to greet [default: 1]
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-h, --help Print help information
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-n, --name <NAME> Name of the person to greet
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-V, --version Print version information
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```
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*(version number and `.exe` extension on windows replaced by placeholders)*
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### Aspirations
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- Out of the box, users get a polished CLI experience
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- Including common argument behavior, help generation, suggested fixes for users, colored output, [shell completions](https://github.com/clap-rs/clap/tree/master/clap_complete), etc
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- Flexible enough to port your existing CLI interface
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- However, we won't necessarily streamline support for each use case
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- Reasonable parse performance
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- Resilient maintainership, including
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- Willing to break compatibility rather than batching up breaking changes in large releases
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- Leverage feature flags to keep to one active branch
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- Being under [WG-CLI](https://github.com/rust-cli/team/) to increase the bus factor
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- We follow semver and will wait about 6-9 months between major breaking changes
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- We will support the last two minor Rust releases (MSRV, currently 1.54.0)
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While these aspirations can be at odds with fast build times and low binary
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size, we will still strive to keep these reasonable for the flexibility you
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get. Check out the
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[argparse-benchmarks](https://github.com/rust-cli/argparse-benchmarks-rs) for
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CLI parsers optimized for other use cases.
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### Selecting an API
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Why use the declarative [Derive API](https://github.com/clap-rs/clap/blob/v3.0.13/examples/tutorial_derive/README.md):
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- Easier to read, write, and modify
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- Easier to keep the argument declaration and reading of argument in sync
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- Easier to reuse, e.g. [clap-verbosity-flag](https://crates.io/crates/clap-verbosity-flag)
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Why use the procedural [Builder API](https://github.com/clap-rs/clap/blob/v3.0.13/examples/tutorial_builder/README.md):
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- Faster compile times if you aren't already using other procedural macros
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- More flexible, e.g. you can look up how many times an argument showed up,
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what its values were, and what were the indexes of those values. The Derive
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API can only report presence, number of occurrences, or values but no indices
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or combinations of data.
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### Related Projects
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- [wild](https://crates.io/crates/wild) for supporting wildcards (`*`) on Windows like you do Linux
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- [argfile](https://crates.io/crates/argfile) for loading additional arguments from a file (aka response files)
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- [clap_complete](https://crates.io/crates/clap_complete) for shell completion support
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- [clap-verbosity-flag](https://crates.io/crates/clap-verbosity-flag)
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- [clap-cargo](https://crates.io/crates/clap-cargo)
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- [concolor-clap](https://crates.io/crates/concolor-clap)
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- [Command-line Apps for Rust](https://rust-cli.github.io/book/index.html) book
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- [`trycmd`](https://crates.io/crates/trycmd): Snapshot testing
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- Or for more control, [`assert_cmd`](https://crates.io/crates/assert_cmd) and [`assert_fs`](https://crates.io/crates/assert_fs)
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## Feature Flags
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### Default Features
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* **std**: _Not Currently Used._ Placeholder for supporting `no_std` environments in a backwards compatible manner.
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* **color**: Turns on colored error messages.
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* **suggestions**: Turns on the `Did you mean '--myoption'?` feature for when users make typos.
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#### Optional features
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* **derive**: Enables the custom derive (i.e. `#[derive(Parser)]`). Without this you must use one of the other methods of creating a `clap` CLI listed above.
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* **cargo**: Turns on macros that read values from `CARGO_*` environment variables.
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* **env**: Turns on the usage of environment variables during parsing.
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* **regex**: Enables regex validators.
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* **unicode**: Turns on support for unicode characters (including emoji) in arguments and help messages.
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* **wrap_help**: Turns on the help text wrapping feature, based on the terminal size.
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#### Experimental features
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**Warning:** These may contain breaking changes between minor releases.
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* **unstable-replace**: Enable [`App::replace`](https://github.com/clap-rs/clap/issues/2836)
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* **unstable-multicall**: Enable [`AppSettings::Multicall`](https://github.com/clap-rs/clap/issues/2861)
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* **unstable-grouped**: Enable [`ArgMatches::grouped_values_of`](https://github.com/clap-rs/clap/issues/2924)
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## Sponsors
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### Gold
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[](https://opencollective.com/clap)
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### Silver
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[](https://opencollective.com/clap)
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### Bronze
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[](https://opencollective.com/clap)
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### Backer
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[](https://opencollective.com/clap)
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