From: "David A. Black" <dblack@...>
Date: 2009-10-11T19:33:28+09:00
Subject: Re: When use self.method_name and when only method_name?

Hi --

On Sun, 11 Oct 2009, Joshua Muheim wrote:

> David A. Black wrote:
>> In fact, the
>> whole private access level depends on it
>
> What do you mean with this exactly?

A private method can only be called without an explicit receiver
(except for =-terminated methods). For example:

   class Baker
     def bake_cake
       make_batter         # private method
       put_in_oven         # private method
       puts "Cake is done!"
     end

     private
     def make_batter
       puts "Privately making the batter!"
     end

     def put_in_oven
       puts "Privately putting the cake in oven!"
     end
   end

   b = Baker.new
   b.bake_cake

In this code, I can call the private methods only when I *don't* have
an explicit receiver, including self. If I try to do this:

   b.make_batter

I get an error. Also, if I rewrite bake_cake like this:

   def bake_cake
     self.make_batter
     put_in_oven
     puts "Cake is done!"
   end

I get an error, because I'm calling make_batter with an explicit
receiver.

So Ruby uses the bareword style of method call to enforce privateness.
The exception is the setter methods (like age=), which always require
an explict receiver. In such cases, the receiver must be "self" (i.e.,
exactly the word "self", not a variable reference to self).


David

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