# A little help needed **URL:** \ **Category:** Ruby\ **Created:** [April 2, 2010, 9:42pm UTC](https://www.ruby-forum.com/t/a-little-help-needed/186239 "2010-04-02T21:42:44Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![homer-16](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/838e76/32.png) [@homer-16](https://www.ruby-forum.com/u/homer-16)\ **Post date:** [April 2, 2010, 9:42pm UTC](https://www.ruby-forum.com/t/a-little-help-needed/186239/1 "2010-04-02T21:42:44Z")
Hi,I’m new here. I have a question: What exactly does the ‘@’ symbol mean when used for the scope of a variable? For instance: @screen=[640,400]. I haven’t found anything explicitly explaining exactly what this does. Thanks! ---
**Author:** ![homer-16](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/838e76/32.png) [@homer-16](https://www.ruby-forum.com/u/homer-16)\ **Post date:** [April 2, 2010, 9:53pm UTC](https://www.ruby-forum.com/t/a-little-help-needed/186239/2 "2010-04-02T21:53:12Z")
On Fri, Apr 2, 2010 at 9:42 PM, Tom S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Hi,I’m new here. > > I have a question: > > What exactly does the ‘@’ symbol mean when used for the scope of a > variable? > For instance: @screen=[640,400]. > > I haven’t found anything explicitly explaining exactly what this does. It means it’s an instance variable of the object that is currently self in that context. For example: class A def initialize @value = 3 end end a = A.new The object referenced by a has an instance variable called @value with value 3. Jesus. ---
**Author:** ![homer-16](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/838e76/32.png) [@homer-16](https://www.ruby-forum.com/u/homer-16)\ **Post date:** [April 2, 2010, 9:56pm UTC](https://www.ruby-forum.com/t/a-little-help-needed/186239/3 "2010-04-02T21:56:43Z")
Oh! I see! So it’s a variable that is automtically given to each instance of that class right? ---
**Author:** ![homer-16](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/838e76/32.png) [@homer-16](https://www.ruby-forum.com/u/homer-16)\ **Post date:** [April 2, 2010, 9:59pm UTC](https://www.ruby-forum.com/t/a-little-help-needed/186239/4 "2010-04-02T21:59:04Z")
> So it’s a variable that is automtically given to each instance of that > class right? Not quite… it’s a variable in the instance that it is declared. So, if you put it in the ‘initialize’ method as seen in that example, it will assign that variable for that instance when it is created. -Jonathan N. ---
**Author:** ![homer-16](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/838e76/32.png) [@homer-16](https://www.ruby-forum.com/u/homer-16)\ **Post date:** [April 2, 2010, 10:15pm UTC](https://www.ruby-forum.com/t/a-little-help-needed/186239/5 "2010-04-02T22:15:53Z")
Jonathan N. wrote: > > So it’s a variable that is automtically given to each instance of that > > class right? > > Not quite… it’s a variable in the instance that it is declared. So, > if you put it in the ‘initialize’ method as seen in that example, it > will assign that variable for that instance when it is created. > > -Jonathan N. So… it’s a variable that can only be used in that instance and nowhere else? such as: Class Test def initialize @x=5 end def testing puts"#{@x}" end end problem=Test.new problem.testing > 5 #however puts"#{@x}" > error ---
**Author:** ![homer-16](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/838e76/32.png) [@homer-16](https://www.ruby-forum.com/u/homer-16)\ **Post date:** [April 2, 2010, 10:25pm UTC](https://www.ruby-forum.com/t/a-little-help-needed/186239/6 "2010-04-02T22:25:25Z")
> problem=Test.new > > problem.testing > > > 5 > > #however > > puts"#{@x}" > > > error Yes, it can only be used within that class. You can, however, create an accessor for it like this: class Test def initialize @x = 5 end attr\_accessor :x end solution = Test.new solution.x (=\>5) solution.x = 6 solution.x (=\>6) -Jonathan N. ---
**Author:** ![homer-16](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/838e76/32.png) [@homer-16](https://www.ruby-forum.com/u/homer-16)\ **Post date:** [April 2, 2010, 10:31pm UTC](https://www.ruby-forum.com/t/a-little-help-needed/186239/7 "2010-04-02T22:31:21Z")
Jonathan N. wrote: > Yes, it can only be used within that class. You can, however, create > an accessor for it like this: > > class Test > def initialize > @x = 5 > end > > attr\_accessor :x > end > > solution = Test.new > solution.x (=\>5) > > solution.x = 6 > solution.x (=\>6) > > -Jonathan N. Yep, already knew that. Thanks for clearing this up for me. I’m creating a game for school you see so I needed to know exacly what that meant. (Now I can understand more of what’s happening in source code) 😉 ---
**Author:** ![homer-16](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/838e76/32.png) [@homer-16](https://www.ruby-forum.com/u/homer-16)\ **Post date:** [April 3, 2010, 2:44am UTC](https://www.ruby-forum.com/t/a-little-help-needed/186239/8 "2010-04-03T02:44:45Z")
On Fri, Apr 2, 2010 at 2:15 PM, Tom S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > puts"#{@x}" > > > error You can also just say @x, here, because puts will convert the objects it receives into strings by calling the to\_s method on them puts “#{@x}” puts @x.to\_s puts @x In this case will all be the same, there is no need to interpolate strings here. At least in 1.9.1 this is true. I tried it in 1.8 and the last one outputted “nil” which is odd, and the only way I can think of that would explain it is that puts checks to see if the variable is nil before calling to\_s, and explicitly outputs “nil” if it is.