ruby-rules

Ruby Rules

These rules come from app/rules/ruby/ in ai-toolkit. They cover the project's standards for coding style, frameworks, patterns, security, and testing in Ruby. Apply them when writing or reviewing Ruby code.

Ruby Coding Style

Naming

• PascalCase: classes, modules.
• snake_case: methods, variables, file names, directories.
• UPPER_SNAKE: constants (MAX_RETRIES = 3).
• Prefix boolean methods with predicate: empty?, valid?, admin?.
• Suffix dangerous methods with !: save!, sort!, strip!.
• Use _ prefix for intentionally unused variables: _unused.

Methods

• Keep methods short: 5-10 lines ideal. Extract helper methods.
• Use keyword arguments for methods with >2 parameters.
• Use default parameter values instead of checking for nil.
• Use def method_name = expression (Ruby 3.0+) for one-liners.
• Prefer each over for loops. Use block-style iteration.
• Return values implicitly (last expression). Use explicit return only for early exit.

Blocks, Procs, Lambdas

• Use { } for single-line blocks. Use do...end for multi-line blocks.
• Use &:method shorthand: names.map(&:upcase).
• Use lambdas for strict argument checking. Use procs for flexible arity.
• Use yield for single-block methods. Use explicit &block for storing/forwarding.

Classes

• Use attr_reader, attr_writer, attr_accessor for simple getters/setters.
• Use Struct for simple data containers. Use Data.define (Ruby 3.2+) for immutable.
• Use modules for mixins: include for instance methods, extend for class methods.
• Use frozen_string_literal: true magic comment at the top of every file.
• Use private / protected keywords to control method visibility.

Collections

• Use map, select, reject, reduce, flat_map for transformations.
• Use each_with_object over inject when accumulating into a mutable object.
• Use dig for safe nested hash/array access: data.dig(:user, :address, :city).
• Use Hash#fetch with default for explicit missing-key handling.
• Use Enumerable#lazy for large collection processing.