Objectの子クラスとその子クラスがincludeしているModuleを階層的に表示するナニカ

object_ancestors.rb

def prefix(depth=1)
  s = ' | '
  s * depth
end

def included_modules(klass, hash)
  modules = Object.const_get(klass).included_modules
  modules.delete(Kernel)
  if modules
    modules.map do |c|
      %(<#{c}>)
    end.join(', ')
  end
end

def ptree(klass, hash, depth)
  puts %(#{prefix(depth)}#{klass} #{included_modules(klass, hash)})

  if hash[klass]
    hash[klass].each do |c|
      ptree(c, hash, depth + 1)
    end
  end
end

hash = Object.constants.select do |c|
  # NOTE: ModuleじゃなくてClassを集める
  Object.const_get(c).class == Class
end.compact.map do |c|
  # NOTE: 親クラスと子クラスのarrayをつくる
  [Object.const_get(c).superclass.to_s, Object.const_get(c).to_s]
end.reduce({}) do |a, pair|
  # NOTE: 親クラスをキーとして値に子クラスを配列を詰める
  a[pair.first] ||= []
  a[pair.first] << pair.last
  a
end

puts 'Object'
puts '------'

hash['Object'].sort.each do |c|
  ptree(c, hash, 1)
end

Object
-----
 | Array <Enumerable>
 | Binding 
 | Data 
 |  | StringIO <IO::generic_writable>, <IO::generic_readable>, <Enumerable>
 | Dir <Enumerable>
 | Encoding 
 | Enumerator <Enumerable>
 | Exception 
 |  | SystemExit 
 |  | StandardError 
 |  |  | FiberError 
 |  |  | ZeroDivisionError 
 |  |  | RegexpError 
 |  |  | ThreadError 
 |  |  | IOError 
 |  |  |  | EOFError 
 |  |  | ArgumentError 
 |  |  |  | UncaughtThrowError 
 |  |  | IndexError 
 |  |  |  | StopIteration 
 |  |  |  |  | ClosedQueueError 
 |  |  |  | KeyError 
 |  |  | TypeError 
 |  |  | RangeError 
 |  |  |  | FloatDomainError 
 |  |  | RuntimeError 
 |  |  | EncodingError 
 |  |  | LocalJumpError 
 |  |  | SystemCallError 
 |  |  | NameError <DidYouMean::Correctable>
 |  |  |  | NoMethodError <DidYouMean::Correctable>
 |  | SignalException 
 |  |  | Interrupt 
 |  | ScriptError 
 |  |  | LoadError 
 |  |  | NotImplementedError 
 |  |  | SyntaxError 
 |  | SystemStackError 
 |  | SecurityError 
 |  | NoMemoryError 
 | FalseClass 
 | Fiber 
 | Hash <Enumerable>
 | IO <File::Constants>, <Enumerable>
 |  | File <File::Constants>, <Enumerable>
 | MatchData 
 | Method 
 | Module 
 |  | Class 
 | Monitor <MonitorMixin>
 | NilClass 
 | Numeric <Comparable>
 |  | Integer <Comparable>
 |  | Float <Comparable>
 |  | Rational <Comparable>
 |  | Complex <Comparable>
 |  | Integer <Comparable>
 |  | Integer <Comparable>
 | Proc 
 | Random <Random::Formatter>
 | Range <Enumerable>
 | Regexp 
 | RubyVM 
 | String <Comparable>
 | Struct <Enumerable>
 | Symbol <Comparable>
 | Thread 
 | Thread::ConditionVariable 
 | Thread::Mutex 
 | Thread::Queue 
 |  | Thread::SizedQueue 
 | ThreadGroup 
 | Time <Comparable>
 | TracePoint 
 | TrueClass 
 | UnboundMethod