Standard Exceptions in Ruby (MRI 1.9 and 1.8) and how to generate them

mri_1_8.rb

ruby-1.8.7-p302 > tree_printer.call tree
Exception
  IRB::Abort
  NoMemoryError
  ScriptError
    LoadError
    NotImplementedError
    SyntaxError
  SignalException
    Interrupt
  StandardError
    ArgumentError
    Exception2MessageMapper::ErrNotRegisteredException
    IOError
      EOFError
    IRB::CantChangeBinding
    IRB::CantReturnToNormalMode
    IRB::CantShiftToMultiIrbMode
    IRB::IllegalParameter
    IRB::IrbAlreadyDead
    IRB::IrbSwitchedToCurrentThread
    IRB::NoSuchJob
    IRB::NotImplementedError
    IRB::Notifier::ErrUndefinedNotifier
    IRB::Notifier::ErrUnrecognizedLevel
    IRB::SLex::ErrNodeAlreadyExists
    IRB::SLex::ErrNodeNothing
    IRB::UndefinedPromptMode
    IRB::UnrecognizedSwitch
    IndexError
      StopIteration
    LocalJumpError
    NameError
      NoMethodError
    RangeError
      FloatDomainError
    RegexpError
    RubyLex::AlreadyDefinedToken
    RubyLex::SyntaxError
    RubyLex::TerminateLineInput
    RubyLex::TkReading2TokenDuplicateError
    RubyLex::TkReading2TokenNoKey
    RubyLex::TkSymbol2TokenNoKey
    RuntimeError
    SecurityError
    SystemCallError
    SystemStackError
    ThreadError
    TypeError
    ZeroDivisionError
  SystemExit
  fatal
 => [Exception]

mri_1_9.rb

ruby-1.9.2-p0 > tree_printer.call tree
BasicObject
  Exception
    IRB::Abort  
    NoMemoryError
    ScriptError 
      LoadError 
      NotImplementedError
      SyntaxError
    SecurityError
    SignalException
      Interrupt
    StandardError
      ArgumentError
      EncodingError
        Encoding::CompatibilityError
        Encoding::ConverterNotFoundError
        Encoding::InvalidByteSequenceError
        Encoding::UndefinedConversionError
      Exception2MessageMapper::ErrNotRegisteredException
      FiberError
      IOError
        EOFError
      IRB::CantChangeBinding
      IRB::CantReturnToNormalMode
      IRB::CantShiftToMultiIrbMode
      IRB::IllegalParameter
      IRB::IrbAlreadyDead
      IRB::IrbSwitchedToCurrentThread
      IRB::NoSuchJob
      IRB::NotImplementedError
      IRB::Notifier::ErrUndefinedNotifier
      IRB::Notifier::ErrUnrecognizedLevel
      IRB::SLex::ErrNodeAlreadyExists
      IRB::SLex::ErrNodeNothing
      IRB::UndefinedPromptMode
      IRB::UnrecognizedSwitch
      IndexError
        KeyError
        StopIteration
      LocalJumpError
      Math::DomainError
      NameError
        NoMethodError
      RangeError
        FloatDomainError
      RegexpError
      RubyLex::AlreadyDefinedToken
      RubyLex::SyntaxError
      RubyLex::TerminateLineInput
      RubyLex::TkReading2TokenDuplicateError
      RubyLex::TkReading2TokenNoKey
      RubyLex::TkSymbol2TokenNoKey
      RuntimeError
      SystemCallError
      ThreadError
      TypeError
      ZeroDivisionError
    SystemExit
    SystemStackError
    fatal
 => [BasicObject]

ruby-standard-exceptions-viewer.rb

exceptions = []
tree = {}
ObjectSpace.each_object(Class) do |cls|
  next unless cls.ancestors.include? Exception
  next if exceptions.include? cls
  next if cls.superclass == SystemCallError # avoid dumping Errno's
  exceptions << cls
  cls.ancestors.delete_if {|e| [Object, Kernel].include? e }.reverse.inject(tree) {|memo,cls| memo[cls] ||= {}}
end

indent = 0
tree_printer = Proc.new do |t|
  t.keys.sort { |c1,c2| c1.name <=> c2.name }.each do |k|
    space = (' ' * indent); space ||= ''
    puts space + k.to_s
    indent += 2; tree_printer.call t[k]; indent -= 2
  end
end
tree_printer.call tree