Private class methods in Ruby

In Ruby instance methods can be marked as private by declaring them below the private section. However, the same does not work for class methods.

class SomeClass

  def method1
    # do something
  end

  private

  def method2
    # do something els
  end

end

The above works fine. Instances (objects) of the class can not call method2 directly.

class SomeOtherClass

  def self.method1
    # do something
  end

  private

  def self.method2
    # do something else
  end

end

In this case however, one can easily call method2 as follows.

SomeOtherClass.method2

To mark class methods as private,  we will need to use private_class_method as shown below.

class SomeOtherClass

  def self.method1
    # do something
  end

  private_class_method :method2 :method3

  def self.method2
    # do something else
  end

  def self.method3
    # do some other things here
  end


end