Clap Scaffolder Skill | Agent Skills

Clap Scaffolder

Generate a complete Clap CLI application with Rust, derive macros, and best practices.

Capabilities

Generate Rust-based Clap CLI projects using derive macros
Create subcommand hierarchies with nested enums
Set up argument parsing with type validation
Configure shell completion generation
Implement colored output with anyhow error handling
Set up cargo workspace and build configurations

Usage

Invoke this skill when you need to:

Bootstrap a new CLI application using Clap
Create a Rust CLI with type-safe argument parsing
Leverage derive macros for declarative command definitions
Build fast, native cross-platform binaries

Inputs

| Parameter | Type | Required | Description | |-----------|------|----------|-------------| | projectName | string | Yes | Name of the CLI project (kebab-case) | | description | string | Yes | Short description of the CLI | | commands | array | No | List of commands to scaffold | | deriveFeatures | array | No | Clap derive features to enable | | colorOutput | boolean | No | Enable colored output (default: true) |

Command Structure

{
  "commands": [
    {
      "name": "run",
      "description": "Run the application",
      "args": [
        { "name": "target", "help": "Target to run", "required": true }
      ],
      "options": [
        { "long": "watch", "short": "w", "help": "Watch for changes" },
        { "long": "port", "short": "p", "value_name": "PORT", "default": "3000" }
      ]
    }
  ]
}

Output Structure

<projectName>/
├── Cargo.toml
├── Cargo.lock
├── README.md
├── .gitignore
├── src/
│   ├── main.rs              # Entry point
│   ├── cli.rs               # Clap definitions
│   ├── commands/
│   │   ├── mod.rs           # Command exports
│   │   └── <command>.rs     # Individual commands
│   ├── config.rs            # Configuration
│   └── error.rs             # Error types
├── tests/
│   └── cli.rs               # CLI integration tests
└── completions/
    ├── _<projectName>       # Zsh completions
    ├── <projectName>.bash   # Bash completions
    └── <projectName>.fish   # Fish completions

Generated Code Patterns

CLI Definition (src/cli.rs)

use clap::{Parser, Subcommand, Args};

#[derive(Parser)]
#[command(name = "<projectName>")]
#[command(author, version, about, long_about = None)]
pub struct Cli {
    /// Enable verbose output
    #[arg(short, long, global = true)]
    pub verbose: bool,

    /// Configuration file path
    #[arg(short, long, global = true)]
    pub config: Option<PathBuf>,

    #[command(subcommand)]
    pub command: Commands,
}

#[derive(Subcommand)]
pub enum Commands {
    /// Run the application
    Run(RunArgs),
    /// Build the project
    Build(BuildArgs),
    /// Generate shell completions
    Completions {
        /// Shell to generate completions for
        #[arg(value_enum)]
        shell: clap_complete::Shell,
    },
}

#[derive(Args)]
pub struct RunArgs {
    /// Target to run
    pub target: String,

    /// Watch for changes
    #[arg(short, long)]
    pub watch: bool,

    /// Port to use
    #[arg(short, long, default_value = "3000")]
    pub port: u16,
}

Main Entry (src/main.rs)

use anyhow::Result;
use clap::Parser;
use colored::Colorize;

mod cli;
mod commands;
mod config;
mod error;

use cli::{Cli, Commands};

fn main() -> Result<()> {
    let cli = Cli::parse();

    // Setup logging based on verbosity
    if cli.verbose {
        env_logger::Builder::from_env(
            env_logger::Env::default().default_filter_or("debug")
        ).init();
    }

    match cli.command {
        Commands::Run(args) => commands::run::execute(args)?,
        Commands::Build(args) => commands::build::execute(args)?,
        Commands::Completions { shell } => {
            generate_completions(shell);
        }
    }

    Ok(())
}

Command Implementation

use anyhow::Result;
use colored::Colorize;

use crate::cli::RunArgs;

pub fn execute(args: RunArgs) -> Result<()> {
    println!("{} Running target: {}", "→".blue(), args.target.green());

    if args.watch {
        println!("{} Watch mode enabled", "!".yellow());
    }

    println!("{} Listening on port {}", "✓".green(), args.port);

    Ok(())
}

Dependencies

[package]
name = "<projectName>"
version = "0.1.0"
edition = "2021"

[dependencies]
clap = { version = "4.4", features = ["derive", "env"] }
clap_complete = "4.4"
anyhow = "1.0"
thiserror = "1.0"
colored = "2.0"
env_logger = "0.10"
log = "0.4"

[dev-dependencies]
assert_cmd = "2.0"
predicates = "3.0"

Workflow

Validate inputs - Check project name, commands structure
Create directory structure - Set up Rust project layout
Generate Cargo.toml - Configure dependencies and metadata
Create CLI definition - Clap derive structs
Generate commands - Individual command modules
Create utilities - Config, error handling
Generate completions - Shell completion scripts
Set up tests - CLI integration tests

Best Practices Applied

Derive macros for declarative definitions
Anyhow for error handling
Colored output for user feedback
Environment variable support
Built-in completion generation
Cross-platform compatible

References

Clap Documentation: https://docs.rs/clap/
Clap GitHub: https://github.com/clap-rs/clap
Rust CLI Book: https://rust-cli.github.io/book/

Target Processes

cli-application-bootstrap
argument-parser-setup
shell-completion-scripts

Agent Skills: Clap Scaffolder

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