ruby-coder

# Ruby Coder

## Overview

This skill provides comprehensive guidance for writing clean, idiomatic Ruby code that follows modern Ruby 3.x syntax, Sandi Metz's 4 Rules for Developers, and established best practices. Apply these standards when creating new Ruby files, implementing features, or refactoring existing code to ensure clarity, maintainability, and adherence to Ruby conventions.

## Core Philosophy

Prioritize:
- **Clarity over cleverness**: Code should be immediately understandable
- **Simplicity**: Prefer simple, readable solutions over clever code
- **Idiomatic Ruby**: Use Ruby's expressive capabilities appropriately
- **Sandi Metz's Rules**: Enforce strict limits to maintain code quality
- **DRY (Don't Repeat Yourself)**: Eliminate duplication thoughtfully
- **Composition over Inheritance**: Design for flexibility and reusability

## Ruby 3.x Modern Syntax

### Naming Conventions

```ruby
# snake_case for methods and variables
def calculate_total_price
  user_name = "David"
end

# CamelCase for classes and modules
module Vendors
  class User
  end
end

# SCREAMING_SNAKE_CASE for constants
MAX_RETRY_COUNT = 3
DEFAULT_TIMEOUT = 30
```

### Hash Shorthand Syntax

Use the shorthand syntax when hash keys match local variable names (requires exact matching between symbol key and variable name):

```ruby
# Modern Ruby 3.x shorthand
age = 49
name = "David"
user = { name:, age: }

# Instead of the verbose form
user = { name: name, age: age }
```

### String Interpolation

Prefer string interpolation over concatenation:

```ruby
# Good - interpolation
greeting = "Hello, #{user_name}!"
message = "Total: #{quantity * price}"

# Avoid - concatenation
greeting = "Hello, " + user_name + "!"
```

### Modern Hash Syntax

Use symbol keys with colon syntax:

```ruby
# Good - modern syntax
options = { timeout: 30, retry: true, method: :post }

# Avoid - hash rocket syntax (only use for non-symbol keys)
options = { :timeout => 30, :retry => true }
```

## Sandi Metz's 4 Rule