building-clis

# Building CLIs

Build professional command-line interfaces across Python, Go, and Rust using modern frameworks with robust argument parsing, configuration management, and shell integration.

## When to Use This Skill

Use this skill when:
- Building developer tooling or automation CLIs
- Creating infrastructure management tools (deployment, monitoring)
- Implementing API client command-line tools
- Adding CLI capabilities to existing projects
- Packaging utilities for distribution (PyPI, Homebrew, binary releases)

Common triggers: "create a CLI tool", "build a command-line interface", "add CLI arguments", "parse command-line options", "generate shell completions"

## Framework Selection

### Quick Decision Guide

**Python Projects:**
- **Typer** (recommended): Modern type-safe CLIs with minimal boilerplate
- **Click**: Mature, flexible CLIs for complex command hierarchies

**Go Projects:**
- **Cobra** (recommended): Industry standard for enterprise tools (Kubernetes, Docker, GitHub CLI)
- **urfave/cli**: Lightweight alternative for simple CLIs

**Rust Projects:**
- **clap v4** (recommended): Type-safe with derive API or builder API for runtime flexibility

For detailed framework comparison and selection criteria, see [references/framework-selection.md](references/framework-selection.md).

## Core Patterns

### Arguments vs. Options vs. Flags

**Positional Arguments:**
- Primary input, identified by position
- Use for required inputs (max 2-3 arguments)
- Example: `convert input.jpg output.png`

**Options:**
- Named parameters with values
- Use for configuration and optional inputs
- Example: `--output file.txt`, `--config app.yaml`

**Flags:**
- Boolean options (presence = true)
- Use for switches and toggles
- Example: `--verbose`, `--dry-run`, `--force`

**Decision Matrix:**

| Use Case | Type | Example |
|----------|------|---------|
| Primary required input | Positional Argument | `git commit -m "message"` |
| Optional configuration | Option | `--config app.ya