Ruby Quick Reference

Written on March 22, 2008 by ceefour

While using Ruby for your projects, you may need some references.

These are some references that might help you in using Ruby:

Language
General Syntax Rules

Comments start with a pound/sharp (#) character and go to EOL.

Ruby programs are sequence of expressions.

Each expression is delimited by semicolons(;) or newlines unless obviously incomplete (e.g. trailing ‘+’).

Backslashes at the end of line does not terminate expression.

Reserved words
alias   and     BEGIN   begin   break   case    class   def     defined
do      else    elsif   END     end     ensure  false   for     if
in      module  next    nil     not     or      redo    rescue  retry
return  self    super   then    true    undef   unless  until   when
while   yield
Type

Basic types are numbers, strings, ranges, regexen, symbols, arrays, and hashes. Also included are files because they are used so often.
Variables
$global_variable
@@class_variable
@instance_variable
[OtherClass::]CONSTANT
local_variable
Standard Library

Ruby comes with an extensive library of classes and modules. Some are built-in, and some are part of the standard library. You can distinguish the two by the fact that the built-in classes are in fact, built-in. There are no dot-rb files for them.

Built-in Library

Class Hierarchy:

Object

Hash

Symbol

IO

File

Continuation

File::Stat

Data

NilClass

Exception (see tree above)

Array

Proc

String

Standard Library

The essentials:

benchmark.rb a simple benchmarking utility

cgi-lib.rb decode CGI data - simpler than cgi.rb

cgi.rb CGI interaction

date.rb date object (compatible)

debug.rb ruby debugger

delegate.rb delegate messages to other object

English.rb access global variables by english names

fileutils.rb file utility methods for copying, moving, removing, etc.

Tools: ruby(Command Line Options, Environment Variables), irb, xmp, ruby-mode, Debugger, rdoc

Mindshare, Idiom and Patterns (Object Design, Other Third-party Libraries)