From: Lucas Holland <hollandlucas@...>
Date: 2007-05-04T13:52:21+09:00
Subject: Re: Top-level

Robert Klemme wrote:
> On 03.05.2007 20:13, Lucas Holland wrote:
>> I'm currently diving a bit deeper into Ruby and I've already asked this
>> question in the IRC (the folks there have been great I think I'm getting
>> it 50%). The question's about top-level methods:
>> 
>> Let's take puts as an example. Puts is inside of the Kernel module,
>> which gets mixed into the Object class. So essentially, it's a private
>> method of Object. When I call puts, I don't specify a receiver, so self
>> is assumed (I think so).
> 
> Correct.
> 
>> In this case self refers to main, an instance
>> of Object, automatically created. So, I'm really calling main.puts. main
>> is an instance of Object, so why is it able to call private methods of
>> Object?
> 
> Um, you explained it already: "puts" is an *instance* method of Object.
>   And since "main" is an instance of Object or one of its subclasses
> (all classes are subclasses of Object!) it has method "puts".  Basically
> the method is only defined private in order to enforce a more function
> like invocation:
> 
> irb(main):001:0> self.puts "foo"
> NoMethodError: private method `puts' called for main:Object
>          from (irb):1
>          from :0
> irb(main):002:0> puts "foo"
> foo
> => nil
> irb(main):003:0>
> 
> Kind regards
> 
>   robert

Hey, it's me again (this time I'm logged in ;-) ). I understand that 
puts is a private instance method of Object and that thus, all instances 
of Object have the method. I also understand that I can only call 
private methods if the receiver is self (by not specifying the 
receiver). So, in this instance, that's the case. When I however create 
a class like so:

class MyClass
  private
  def test
    puts "hello, world"
  end
  public
  def pub
   test
  end
end

I am able to call the test method because of the implicit receiver, 
self. In this case, however, self refers to the class MyClass (which is 
an instance of Class, as far as I know). But MyClass is an instance of 
Class, not of itself, so why can it suddenly call *instance* methods of 
itself?

Thanks in advance,

Lucas

-- 
Posted via http://www.ruby-forum.com/.