Where to place private methods in Ruby?

Question

Most of the blogs or tutorials or books have private methods at the bottom of any class/module. Is this the best practice?

I find having private methods as and when nece

Answer 1

There's also the option to prepend private to the method definition since Ruby 2.1.

class Example

 def xmethod
 end

 private def ymethod
 end

 private def zmethod 
 end

end

Looking at the definition, you instantly know if a method is private, no matter where in the file it's defined. It's a bit more typing (if you don't autocomplete) and not all your defs will be nicely aligned.

Answer 2

You don't need to put public or private above each method. I usually put all of my private methods at the bottom of my class. Also, don't have to explicitly say public as methods are public by default. For example:

class FooBar

  def some_public_method
  end

  def another_public_method
  end

private

  def some_private_method
  end

  def another_private method
  end

end

Answer 3

One style is to group methods together so that you only use private and protected once per class at most. Another style is to specify visibility right after the method definition:

class Example
  def my_private_method
  end
  private :my_private_method

  def my_public_method
  end
end

As of Ruby 2.1.0 def returns the method name as a symbol, so a more streamlined style is possible:

class Example
  private def my_private_method
  end

  def my_public_method
  end

  protected def my_protected_method
  end

  private_class_method def self.my_private_class_method
  end
end

(Note that we use private_class_method for class methods -- otherwise we'd get NameError: undefined method since private expects an instance method. Even when using it as a macro like in the original example it only affects the visibility of instance methods.)

I like this inline visibility style best, as it allows you to organize methods as you wish. It decreases the risk of adding a new method in the wrong place and inadvertently making it private.

As for the class method syntax, you can handle it this way instead:

class Example
  private def my_private_method
  end

  class << self
    private def my_private_class_method
    end
  end
end

Answer 4

I think that public methods is a some kind of interface of the object, and it's logical to place them on the most prominent place i.e. in the top of file.