Question

I have a few .rb files and I want to use the same variables in all of them. Let’s say variable test_variable = "test" should be accessible from all my .rb files. How can I achieve that?

I created settings.rb file with test_variable = "test" then used require 'settings' in another .rb file, but it didn’t work. I would like to use require not load.

I tried to make the variable global by prefixing the variable name with $, but I am still getting undefined local variable or method 'test_variable' for main:Object (NameError).

Answer 1

1. Constants (which include modules and classes) are added to the shared global environment:

   phrogz$ cat constants1.rb 
   TEST_VARIABLE = "test"
   
   phrogz$ cat constants2.rb 
   require_relative 'constants1'
   p TEST_VARIABLE
   
   phrogz$ ruby constants2.rb 
   "test"
   

2. Instance variables declared in main are all part of the same main:

   phrogz$ cat instance1.rb 
   @test_variable = "test"
   
   phrogz$ cat instance2.rb 
   require_relative 'instance1'
   p @test_variable
   
   phrogz$ ruby instance2.rb 
   "test"
   

3. Global variables are also all part of the same environment (tested in 1.8.6, 1.8.7, and 1.9.2):

   phrogz$ cat global1.rb 
   $test_variable = "test"
   
   phrogz$ cat global2.rb 
   require_relative 'global1'
   p $test_variable, RUBY_DESCRIPTION
   
   phrogz$ ruby global2.rb 
   "test"
   "ruby 1.9.2p180 (2011-02-18 revision 30909) [x86_64-darwin10.7.0]"