gistfile1.rb

# eval with method definition is used to prevent warnings in some situations

DEFINEE = <<-CODE
  eval 'def __; end'
  it = method(:__).owner rescue instance_method(:__).owner
  eval 'undef __'
  it
CODE

self # => main
eval DEFINEE # => Object

class Foo
  self # => Foo
  eval DEFINEE # => Foo

  def bar
    self # => instance of Foo
    eval DEFINEE # => Foo
  end
end

Foo.instance_eval do
  self # => Foo
  eval DEFINEE # => singleton class of Foo
end

Foo.class_eval do
  self # => Foo
  eval DEFINEE # => Foo
end