CODEWITHSUNDEEP
ruby
Mezbah
Mezbah

Reputation: 1267

Difference between constant variables and global variables

What is the difference between constant variables and global variables?

CONSTANT = 100
$global = 100

I read this question but I can't understand.

Upvotes: 0

Views: 1299

Answers (1)

dax
dax

Reputation: 10997

Global variables are global, meaning that even if you put them in a class which is very specifically scoped, they're still available everywhere. They are also explicitly variables (meaning one should not be surprised if their value changes).

For example:

module TopLevel
  module MiddleLevel
    module LowLevel
      class SpecificSomething

        $my_global = "duff man says a lot of things"

      end
    end
  end
end


module TopLevel
  def self.global
    p $my_global
  end
end

TopLevel.global   
#=> "duff man says a lot of things"

Constants are accessible where they are defined - that is, they are NOT global. They are also constants (as the link you provided points out), so one would NOT expect them to change (although ruby does allow them to be changed).

Upvotes: 3

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