特異クラスについて

gistfile1.rb

module Piyo
	def piyo_func
		'piyo_func'
	end
end

class Hoge
	include Piyo
	def initialize
		class << self
			def obj_sing_func
				p "obj_sing_func"
			end
		end
	end
	def inst_func
		p "inst_func"
	end
end

class << Hoge
	def class_sing_func
		p "class_sing_func"
	end
end

def Hoge.sing_func2
	p "sing_func2"
end

hoge = Hoge.new

def hoge.sing_func
	p "sing_func"
end

p "-----object-----"
p "  #{hoge}"
p "    methods"
p "      #{hoge.methods - Object.new.methods - hoge.methods(false)}"
p "    singleton_methods"
p "      #{hoge.methods false}"
p "-----class-----"
p "  #{Hoge}"
p "    methods"
p "      #{Hoge.methods - Class.new.methods - Hoge.methods(false)}"
p "    singleton_methods"
p "      #{Hoge.methods false}"
p Hoge.ancestors
p "-----object's singleton class-----"
obj_sing = class << hoge
	self
end
p "  #{obj_sing}"
p "    methods"
p "      #{obj_sing.methods - Class.new.methods - obj_sing.methods(false)}"
p "    singleton_methods"
p "      #{obj_sing.methods false}"
p obj_sing.ancestors
p "-----class's singleton class-----"
class_sing = class << Hoge
	self
end
p "  #{class_sing}"
p "    methods"
p "      #{class_sing.methods - Class.new.methods - Module.methods - class_sing.methods(false)}"
p "    singleton_methods"
p "      #{class_sing.methods false}"
p class_sing.ancestors
csf = Hoge.method :class_sing_func
p "class_sing_func method's owner is #{csf.owner}"
p "class_sing.methods.grep /class_sing_func/ is #{class_sing.methods.grep /class_sing_func/}"

実行結果

"-----object-----"
" #Hoge:0x966c7dc"
" methods"
" [:inst_func, :piyo_func]"
" singleton_methods"
" [:obj_sing_func, :sing_func]"
"-----class-----"
" Hoge"
" methods"
" []"
" singleton_methods"
" [:class_sing_func, :sing_func2]"
[Hoge, Piyo, Object, Kernel, BasicObject]
"-----object's singleton class-----"
" #Class:#Hoge:0x966c7dc"
" methods"
" []"
" singleton_methods"
" [:class_sing_func, :sing_func2]"
[Hoge, Piyo, Object, Kernel, BasicObject]
"-----class's singleton class-----"
" #Class:Hoge"
" methods"
" []"
" singleton_methods"
" []"
[Class, Module, Object, Kernel, BasicObject]
"class_sing_func method's owner is #Class:Hoge"
"class_sing.methods.grep /class_sing_func/ is []"