module Unparser::AbstractType::AbstractMethodDeclarations

def abstract_method(*names)
  names.each(&method(:create_abstract_instance_method))
  self
end

def abstract_singleton_method(*names)
  names.each(&method(:create_abstract_singleton_method))
  self
end

def create_abstract_instance_method(name)
  define_method(name) do |*|
    fail NotImplementedError, "#{self.class}##{name} is not implemented"
  end
end

def create_abstract_singleton_method(name)
  define_singleton_method(name) do |*|
    fail NotImplementedError, "#{self}.#{name} is not implemented"
  end
end