Yarn has used a library called Clipanion to power its CLI ever since the Berry codebase. Where other frameworks tend to either use functional dedicated APIs to declare their commands, Clipanion attempts to provide a more intuitive and user-friendly experience, while remaining highly integrated with TypeScript.

The same is true in the ZPM codebase, as we ported Clipanion over to Rust (repository here). The syntax is similar to the TypeScript implementation of Clipanion, with some twists and new capabilities.

Example

use clipanion::cli;

#[cli::command]
#[cli::path("commit")]
#[cli::category("Miscellaneous commands")]
struct MyCommand {
  #[cli::option("-v,--verbose")]
  verbose: bool,

  #[cli::option("-m,--message")]
  message: Option<String>,

  all: Vec<String>,
}

impl MyCommand {
  fn run(&self) -> Result<(), String> {
    // ...
    Ok(())
  }
}

Typed parameters

Clipanion supports typed parameters out of the box. Any type that implements the FromStr trait can be used as a parameter. This is for example the case of the Ident / Descriptor / Locator types:

#[cli::command]
#[cli::path("add")]
struct AddCommand {
  packages: Vec<Ident>,
}

Documentation

Clipanion will leverage Rust doc comments to generate documentation for each command. The documentation will be displayed in the help output of the CLI:

/// Commit changes to the repository.
///
/// This command will commit all changes to the repository.
#[cli::command]
#[cli::path("commit")]
#[cli::category("Miscellaneous commands")]
struct CommitCommand {
  /// Verbose mode.
  #[cli::option("-v,--verbose")]
  verbose: bool,

  /// Commit message.
  #[cli::option("-m,--message")]
  message: Option<String>,

  /// Files to commit.
  all: Vec<String>,
}