instance_eval and class_eval 1

gistfile1.rb

String.instance_eval do
  def from_instance_eval
    self
  end
end

String.class_eval do
  def from_class_eval
    self
  end
end

p String.from_instance_eval      #String
p "string".from_class_eval       #"string"

begin
  String.from_class_eval
rescue Exception  => e
  p e                            # => #<NoMethodError: undefined method `from_class_eval' for String:Class>
end

begin
  "string".from_instance_eval
rescue Exception  => e
  p e                            # => #<NoMethodError: undefined method `from_instance_eval' for "string":String>
end