Crowdfund is a Ruby program developed based on Pragmatic Studio's Ruby Programming hands-on video course, and distributed as a Ruby gem. This program has been developed using all the strengths of Ruby including the following. Ruby Programming Environment * Installing Ruby on your favorite operating system (free exercise) * Running Ruby using the interactive Ruby shell (irb) and writing Ruby program files * Using Ruby's documentation system to get help * Installing external Ruby libraries using RubyGems * Troubleshooting common problems Ruby Language Constructs * Expressions and variables * Numbers, string, and symbols (free video & exercise) * Loops and conditional expressions * Arrays and hashes (free video & exercise on hashes) * Classes, modules, and structs Object-Oriented Programming * Using built-in Ruby classes * Defining your own classes with state and behavior (free video & exercise) * Creating unique objects * Telling objects what to do by calling methods * Modeling class-level inheritance relationships * Sharing code with mixins Object-Oriented Design Principles * Encapsulation * Separation of concerns * Polymorphism * Don't Repeat Yourself * Tell, Don't Ask Blocks and Iterators * Calling built-in methods that take blocks * Writing your own methods that yield to blocks * Implementing custom iterators * Effectively using blocks in your programs Organizing Ruby Code * Creating a Ruby project structure * Separating source files for easier reuse and testing * Namespacing to avoid naming clashes * Input/Output * Reading data from files * Writing data to files * Creating an interactive console prompt * Handling command-line input Unit Testing * Writing and running unit tests with RSpec * Test-driven development and the red-green-refactor cycle * Stubbing methods to control tests * Refactoring code, safely! Distribution * Conforming to RubyGems conventions * Writing a GemSpec * Building a RubyGem * Publishing a RubyGem to a public server Ruby Programming Idioms