From: Justin Collins <collinsj@...>
Date: 2006-07-26T06:00:54+09:00
Subject: Re: "Self" confusion

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Sch�le Daniel wrote:
>>> class Yoghurt
>>>  def self.a
>>>    "yoghurt self"
>>>  end
>>>  def Yoghurt.a
>>>    "yoghurt"
>>>  end
>>>
>>>  p Yoghurt.a
>>>  p self.a
>>> end
>
> I am not Ruby expert, but isn't Yogurt.a and self.a the same thing?
> Then the last one simply overwrites the preceding one.
>
> From this I think that
> Object.a and self.a should act similary, don't they?
>
>
>
> -- 
> Daniel
>
Yes it is exactly the same _if_ you are inside the definition of the 
class. That is why I was trying to say that the top level of Ruby cannot 
be inside the definition of Object, because then

p self.a

would be the same as

p Object.a

but it isn't, because we are not in a class definition. However,

def self.a
    "Hi from self"
end

is the same as

def a
    "Hi from self again"
end

and the latter will overwrite the first, as we are defining methods for 
this instance of the class.

 From Pickaxe 1:

" At the top level, we're executing code in the context of some 
predefined object. When we define methods, we're actually creating 
(private) singleton methods for this object. Instance variables belong 
to this object. And because we're in the context of |Object|, we can use 
all of |Object|'s methods (including those mixed-in from |Kernel|) in 
function form. This explains why we can call |Kernel| methods such as 
|puts| at the top level (and indeed throughout Ruby): these methods are 
part of every object."


-Justin

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