Variables, Misc

• Variables are references to objects

• Variable declarations are not needed
• Undefined value for a variable: nil
  
• Integers can be used without having to worry about their internal representation (size); automatically converted as needed

Prefixes

• Local variable: myVar
• Global Variable: $myVar
• Instance variable: @myVar
• Class variable: @@myVar

• Default global variable: $_
• Global variable for raised exception: $!

Case

• Local variables, methods, and method parameters should start with a lowercase letter or with an underscore
• Classes, modules, and constants should start with an uppercase letter