Ruby Documentation

Learn how to find and use official Ruby documentation and API references.

Beginner 1 min read

Ruby Documentation

Master Ruby's documentation system and learn how to find help, understand method signatures, and explore the Ruby ecosystem effectively.

Built-in Documentation Tools

ri (Ruby Information): Command-line tool for viewing Ruby documentation

ri Command

Basic ri Usage
# Get help for a method
ri String#upcase

# Get help for a class
ri Array

# Search for methods
ri -T upcase

# List all classes
ri -l
Example ri Output
$ ri String#upcase

= String#upcase

(from ruby core)
=== Implementation from String

------------------------------------------------------------------------------
str.upcase -> new_str

Returns a copy of str with all lowercase letters replaced with their
uppercase counterparts.

Getting Help in IRB

IRB Help Commands
irb(main):001:0> help
irb(main):002:0> "hello".methods
irb(main):003:0> "hello".method(:upcase)
irb(main):004:0> "hello".method(:upcase).source_location

Online Documentation Resources

Official Ruby Documentation

Features
  • Complete API reference
  • Method signatures
  • Code examples
  • Version-specific docs

Community Resources

Features
  • User comments
  • Better search
  • Modern interface
  • Community examples

How to Read Ruby Documentation

Understanding Method Signatures

Method Signature Breakdown
str.gsub(pattern, replacement) → new_str
│ │ │ │ └─ Return type
│ │ │ └─ Parameter name
│ │ └─ Parameter name
│ └─ Method name
└─ Object type
Common Notation
  • → - Returns
  • ? - Boolean return (true/false)
  • ! - Modifies the object
  • * - Variable arguments
  • = - Default parameter value

Gem Documentation

Finding Gem Documentation

Using gem server
# Start gem documentation server
gem server

# Visit http://localhost:8808 in your browser
# Browse all installed gems
Online Gem Resources

Documentation Best Practices

Effective Documentation Reading

  • Start with examples: Look for code examples first
  • Read method signatures: Understand parameters and return values
  • Check related methods: Explore similar methods in the same class
  • Use IRB to test: Try examples in IRB to understand behavior
  • Bookmark useful docs: Keep links to frequently used documentation

Common Documentation Mistakes

  • Not reading the full description: Skim through important details
  • Ignoring parameter types: Don't check what types of arguments are expected
  • Not testing examples: Don't verify examples in IRB
  • Overlooking edge cases: Miss important behavior notes

What's Next?

Continue Your Ruby Journey

  1. Practice with ri: Use ri command to explore Ruby methods
  2. Bookmark resources: Save useful documentation links
  3. Learn Variables: Understand different types of variables
  4. Explore Data Types: Master strings, numbers, arrays, and hashes
  5. Study Methods: Learn how to define and use methods