From: 7stud -- <bbxx789_05ss@...>
Date: 2009-04-29T08:34:42+09:00
Subject: Re: Why does attr_accessor in module require 'self.'?

7stud -- wrote:
> class B
>   def a
>     @a
>   end
> 
>   def a=(val)
>     @a = val
>   end
> 
>   def bar
>     a = "bar"  #<----****
>   end
> 
>   def baz
>     self.a = "baz"
>   end
> 
>   def foo
>     a = 10
>   end
> end
> 
> b = B.new
> puts b.bar
> puts b.a
> puts b.baz
> puts b.a
> 
> 
> --output:--
> bar
> nil
> baz
> baz
> 
> 
> All of which I guess has nothing to do with the op's question.  The op 
> correctly identified that self.a = "baz" calls the a= method, but that a 
> = "bar" does not.   I guess I would pose this question to the op: when 
> have you ever been able to access the a= method in a class without using 
> the format some_obj.a = ?

I guess the idea here:

>   def bar
>     a = "bar"  #<----****
>   end
> 
>   def baz
>     self.a = "baz"
>   end

is that when you call a method without a receiver, self is implied.  So 
the bar method would be equivalent to:

>   def bar
>     self. a = "bar"  #<----****
>   end
> 

Therefore bar and baz have the same format and should do the same thing. 
But...

John Barnette wrote:
> Ruby automatically creates local variables upon
> assignment.

which might be explained further(though perhaps wrongly) by saying: 
before ruby can attach 'self.' to the front of 'a' in the bar method:

>   def bar
>     a = "bar"
>   end

the parser tells ruby that it should create a local variable called 'a' 
instead and assign it the value on the right of the equals sign.  As a 
result unadorned names, for example 'a' vs. 'obj.a', that appear to the 
left of an equals sign cause ruby to create a local variable and assign 
the local variable the value to the right of the equals sign.

-- 
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