pub_prot_priv.rb

class C
  def pub
    :pub
  end
  
protected
  def prot
    :prot
  end
  
private
  def priv
    :priv
  end
end

c = C.new

c.respond_to?(:pub)   # => true
c.respond_to?(:prot)  # => true
c.respond_to?(:priv)  # => false

c.pub                        # => :pub
c.prot rescue "is protected" # => "is protected"
c.priv rescue "is private"   # => "is private"