ruby - What is `singleton_class` method in class and object? -

i defined methods specific_data1 , specific_data2 in meta class, , expected these methods belong singleton class:

class user   def user.specific_data1     "user specific data defined on user"   end   class << self     def specific_data2       "user specific data defined in meta class"     end   end end 

but neither of methods found in:

user.singleton_class.methods 

please me understand singleton_method on user class , how useful.

object#methods returns methods of object. methods defined in class aren't methods of class object, methods of class's instances.

this has nothing singleton classes, it's true classes:

class foo   def bar; end end  foo.methods.include?(:bar) # => false  foo.new.methods.include?(:bar) # => true  foo.instance_methods # => [:bar] 

here's how works example:

user.methods.grep(/specific/) # => [:specific_data1, :specific_data2]  user.singleton_methods # => [:specific_data1, :specific_data2]  user.singleton_class.instance_methods.grep(/specific/) # => [:specific_data1, :specific_data2]