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

1. Validate inputs - Check project name, commands structure
2. Create directory structure - Set up Rust project layout
3. Generate Cargo.toml - Configure dependencies and metadata
4. Create CLI definition - Clap derive structs
5. Generate commands - Individual command modules
6. Create utilities - Config, error handling
7. Generate completions - Shell completion scripts
8. 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