# Using "require" in irb, where did my variables go!? **URL:** \ **Category:** Ruby\ **Created:** [June 1, 2010, 4:23am UTC](https://www.ruby-forum.com/t/using-require-in-irb-where-did-my-variables-go/189441 "2010-06-01T04:23:54Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![azzoti](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/2acd7d/32.png) [@azzoti](https://www.ruby-forum.com/u/azzoti)\ **Post date:** [June 1, 2010, 4:23am UTC](https://www.ruby-forum.com/t/using-require-in-irb-where-did-my-variables-go/189441/1 "2010-06-01T04:23:54Z")
Hello, I have a somewhat basic question: lets say that in my working directory I have a file called my\_vars.rb. It contains: x = 5.0 puts “your variable x is #{x}” Now, I fire up irb in my command window, and type in require “my\_vars.rb” Which outputs, as expected, your variable x is 5.0 =\> true Now, I want to access that variable again, so I enter in: puts x and I get an error saying that x is undefined. It’s like it was temporarily there in memory, but then once it was used, it got thrown away! Does anyone know how to load in a file and keep using the variables that were in said file? Thanks! ---
**Author:** ![azzoti](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/2acd7d/32.png) [@azzoti](https://www.ruby-forum.com/u/azzoti)\ **Post date:** [June 1, 2010, 10:53am UTC](https://www.ruby-forum.com/t/using-require-in-irb-where-did-my-variables-go/189441/2 "2010-06-01T10:53:34Z")
Tim A. wrote: > Hello, > > I have a somewhat basic question: lets say that in my working directory > I have a file called my\_vars.rb. > > It contains: > x = 5.0 > puts “your variable x is #{x}” > > Now, I fire up irb in my command window, and type in > require “my\_vars.rb” > > Which outputs, as expected, > your variable x is 5.0 > =\> true > > Now, I want to access that variable again, so I enter in: > puts x > > and I get an error saying that x is undefined. It’s like it was > temporarily there in memory, but then once it was used, it got thrown > away! Does anyone know how to load in a file and keep using the > variables that were in said file? > > Thanks! You could define x as a global variable $x e.g.: #in my\_vars.rb $x = 5 puts “your variable x is #{$x}” ---
**Author:** ![azzoti](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/2acd7d/32.png) [@azzoti](https://www.ruby-forum.com/u/azzoti)\ **Post date:** [June 1, 2010, 12:30pm UTC](https://www.ruby-forum.com/t/using-require-in-irb-where-did-my-variables-go/189441/3 "2010-06-01T12:30:34Z")
On Mon, May 31, 2010 at 9:23 PM, Tim A. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > require “my\_vars.rb” > away! Does anyone know how to load in a file and keep using the > variables that were in said file? > > ## Thanks! > > Posted via [http://www.ruby-forum.com/](http://www.ruby-forum.com/). Using globals to allow locals to talk across files seems pretty shaky. Why do you need to be able to do this? Probably there is a better way. Perhaps put all that code into one file. Perhaps put it into a method, and have it return the variables of interest (you can conditionally invoke the method if the file is required vs if the file is the primary program by comparing $0 to **FILE** ) ---
**Author:** ![azzoti](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/2acd7d/32.png) [@azzoti](https://www.ruby-forum.com/u/azzoti)\ **Post date:** [June 1, 2010, 6:24pm UTC](https://www.ruby-forum.com/t/using-require-in-irb-where-did-my-variables-go/189441/4 "2010-06-01T18:24:49Z")
On Jun 1, 2010, at 4:23 AM, Tim A. wrote: > require “my\_vars.rb” > away! Does anyone know how to load in a file and keep using the > variables that were in said file? > > Thanks! There is a way around this, although I think that the “usual” solutions (wrapping this data into a proper object or method) are much better. All code in Ruby is evaluated inside the context of an object. In other terms: self is always defined. Code outside of class statements, module statements and some special statements that change the binding is evaluated inside the toplevel object (called “main”). “main” is just a normal object and we can thus set instance variables: File: test.rb @b = 42 File: inc.rb require “test” puts @b #=\> prints 42 Those instance variables can only be accessed in the toplevel context and not in any other object or class. I don’t think this is a good way to do it, but it is a nice way of illustrating how far “everything is an object” is rooted into ruby. Gruß, Skade ---
**Author:** ![azzoti](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/2acd7d/32.png) [@azzoti](https://www.ruby-forum.com/u/azzoti)\ **Post date:** [June 2, 2010, 12:17am UTC](https://www.ruby-forum.com/t/using-require-in-irb-where-did-my-variables-go/189441/5 "2010-06-02T00:17:15Z")
----- “Tim A.” [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > require “my\_vars.rb” > away! Does anyone know how to load in a file and keep using the > variables that were in said file? > > Thanks! The basic construct that you are discovering here is variable scope. It is not that irb lost your variable or ever had it defined in memory. In fact this problem has nothing to do with irb as the following demonstrates: wes:~\> cat \> a.rb \<\< EOF > x = ‘Hi’ > puts x > EOF > wes:~\> cat \> b.rb \<\< EOF > require ‘a’ > > puts “in b #{x}” > EOF > wes:~\> ruby a.rb > Hi > wes:~\> ruby b.rb > Hi > b.rb:3: undefined local variable or method `x’ for main:Object > (NameError) The variable is only available locally in the original script a.rb. Tthe second script has no knowledge of this variable and it raises the NameError exception. If you want the variable to be available to both script define a global: wes:~\> cat a.rb $x = ‘Hi’ puts $x wes:~\> cat b.rb require ‘a’ puts “in b #{$x}” wes:~\> ruby b.rb Hi in b Hi I wouldn’t recommend using global variables in your code but I write this to illustrate the point. You should read more about variable scope here: [Programming Ruby: The Pragmatic Programmer's Guide](http://ruby-doc.org/docs/ProgrammingRuby/)