puts self    #main
puts self.class #Object

def tell_me_who
    puts self
end
tell_me_who  #main

Error:test.rb:8: undefine: undefined local variable or method `ask' for main:Object (NameError)

puts self    #main
puts self.class #Object
def self.method_missing(name,*arg)
    puts "#{name} is not exist!"
end
puts ask   #ask is not exist!

def self.method_missing(name,*arg)
    1.times do 
        puts method_name=name
    end
    puts "#{method_name} is not exist!"
end

ask #变量或者方法