Gotchas

• variables hold references to objects
  • a=[1,2,3]; b=a; b[0]=0 #a->[0,2,3]
• So you need to use an object's 'clone' or 'dup' method to copy
  • a=[1,2,3]; b=a.dup; b[0]=0 #a is unchanged, b->[0,2,3]
• little or no differentiation between runtime and compile time
  • Advantage: you can do things like conditional mixins

    • class Machine
        case RUBY_PLATFORM 
          when /linux/i
            include LinxFuncs
          when /windows/i
            include WinFuncs
          when /macosx/i
            include MacOSXFuncs
          end
       ...
       end
      

• Disadvantage: You've got to define routines prior to using them