From: Benjohn Barnes <benjohn@...>
Date: 2006-03-17T09:05:27+09:00
Subject: Re: Scope of an @variable


On 15 Mar 2006, at 00:54, Jeff Cohen wrote:

> rtilley wrote:
>> This may be wrong, but I like to think of @@ as a class variable  
>> and @
>> as a method variable. @@ is accessible by any method in the class  
>> and @
>> is accessible by the method only.
>
> You're close. @ are instance variables.  Any instance method in your
> class can
> access them.

You can also access @ variables from a class method - ie  
ClassName.function; @a_variable; end. They are local to each class  
within a hierarchy, rather than @@ which would be shared among  
classes in the hierarchy.

So:

class X
	def X.var;
		@var
	end

	def X.var=(v)
		@var=v
	end
end

class Y<X;end

X.var=10
Y.var=20
X.var	=> 10
Y.var	=> 20

Cheers,
	Benjohn