Ruby

Let’s consider the following code:

module M extend self def m_i puts "m_i" end def m puts "include? = [#{singleton_methods.include?(:m_i)}]" puts "call = [#{singleton_method(:m_i).call}]" rescue puts $! end end 

it prints:

# include? = [true] # undefined singleton method `m_i' for `M' 

The method is listed under singleton_methods while the call to it via singleton_method raises an error.