Ruby Study Notes

ActiveRecord Basics

An introduction to Rails' object-relational mapper, covering models, migrations, associations, validations, and the query interface used to interact with a dat…

Arrays in Ruby

An in-depth look at Ruby's Array class — ordered, index-based collections that can hold mixed types and expose a huge Enumerable-powered method set.

attr_accessor and Instance Variables

Learn how instance variables hold per-object state in Ruby, and how attr_accessor, attr_reader, and attr_writer generate boilerplate getter and setter methods.

Blocks, Procs, and Lambdas

Explore Ruby's three flavors of closures -- blocks, Procs, and lambdas -- and how they differ in argument strictness, return semantics, and reusability.

Bundler and Gems

Understand how RubyGems packages and distributes Ruby libraries, and how Bundler locks dependency versions with a Gemfile and Gemfile.lock for reproducible bui…

Case Expressions

How Ruby's case/when expression uses the triple-equals operator for flexible pattern matching against classes, ranges, regexes, and values.

Classes and Objects in Ruby

Learn how Ruby defines classes as blueprints for objects, covering the `class` keyword, `initialize`, instance methods, and how everything in Ruby is an object.

Common Ruby Pitfalls

A tour of frequent Ruby mistakes — mutable defaults, frozen string surprises, nil handling, and block/proc return semantics — with fixes for each.

Comparable and Enumerable Modules

See how Ruby's Comparable and Enumerable modules let a class gain dozens of methods for free by implementing just one core method each: `<=>` or `each`.

Conditional Statements in Ruby

How to control program flow in Ruby with if/elsif/else, unless, ternary expressions, and modifier conditionals, plus Ruby's truthiness rules.

Custom Exceptions in Ruby

Learn to design your own exception classes by subclassing StandardError, giving callers precise, catchable error types instead of generic RuntimeErrors or stri…

Custom Iterators

Learn how to build your own iterator methods with yield and Enumerator, giving your classes the same each/map/select power that Ruby's built-in collections enj…

define_method and Metaprogramming

Discover how define_method, class_eval, and instance_variable_get/set let Ruby programs write code that writes code, powering DSLs, ORMs, and dynamic accessor…

Defining Methods

How to define methods in Ruby using def, including implicit return values, naming conventions (?, !), visibility, and how methods differ from blocks.

Duck Typing in Ruby

Explore Ruby's duck typing philosophy — objects are defined by the methods they respond to, not by their class — and how it shapes idiomatic, flexible Ruby cod…

each, map, and select

Master the three most commonly used Enumerable methods — each for side effects, map for transformation, and select for filtering — and when to reach for which.

Enumerable Deep Dive

Go beyond map and select to explore Enumerable's full toolkit — sort_by, group_by, partition, each_with_object, lazy enumerators, and more — for expressive col…

Exception Handling in Ruby

Understand Ruby's begin/rescue/ensure/raise vocabulary for handling errors gracefully, including exception hierarchies, retry, and best practices for robust co…

Hashes in Ruby

How Ruby's Hash class stores key-value pairs, including modern literal syntax, symbol keys, default values, and the Enumerable methods it inherits.

Hello World and Ruby Syntax

Write your first Ruby program and learn the fundamental syntax conventions: statements, indentation, method calls, and file structure.

Inheritance in Ruby

See how Ruby classes extend one another with single inheritance, how `super` calls parent implementations, and how method resolution order determines which met…

Installing Ruby and Using IRB

How to install Ruby with a version manager, verify your setup, and use IRB (Interactive Ruby) to experiment with code in real time.

Intro to Ruby on Rails

An overview of the Rails web framework, its MVC architecture, and the convention-over-configuration philosophy that lets developers build database-backed apps…

Loops in Ruby

A tour of Ruby's repetition constructs — while, until, for, loop, and the more idiomatic times/each iterators — with guidance on which one to reach for.