From: Lars Haugseth <ruby-talk@...>
Date: 2012-09-19T23:11:30+09:00
Subject: Re: Class variables

On 09/19/2012 03:03 PM, Jeroen Lodewijks wrote:
> Jan E. wrote in post #1076455:
>
>> class Test {
>>
>>    int var = 5;
>>
>>    void show() {
>>      System.out.println(var);
>>    }
>>
>> }
>
> Hi all,
>
> This is exactly the question that I also wanted to ask, being new to
> Ruby. I just registered 5 min ago and see almost the first post is the
> very same probem.
>
> What I want to do achieve is: I want a variable known throughout the
> scope of the class but that is *not* always the same variable if you
> instanciate a new object of the class (I like to achieve what the java
> code above does).
>
> For instance:
>
> class Test
>       var = 5
>
>       def show
>           puts var
>       end
>
>       def set(value)
>           var = value
>       end
> end
>
> test1 = Test.new
> test1.set 10
>
> test2 = Test.new
> test2.set 20
>
> test1.show
> test2.show
>
> Should show 10 and 20
>
> How do I do this?

class Test
   attr_accessor :var

   def initialize
     @var = 5
   end
end

test1 = Test.new
test1.var = 10

test2 = Test.new
test2.var = 20

test3 = Test.new

puts test1.var  # => 10
puts test2.var  # => 20
puts test3.var  # => 5

The attr_accessor statement creates the var= and var methods for setting 
and getting the value of the @var instance variable. You can set it to 
some default value for new instances in the initialize method.

-- 
Lars Haugseth