ruby and references. Working with fixnums

You could pass an array with a single number, like [1], or a hash like {value: 1}. Less ugly than a string, as your number itself remains a number, but less overhead than a new class...

Ruby will always pass-by-reference (because everything is an object) but Fixnum lacks any methods that allow you to mutate the value. See "void foo(int &x) -> Ruby? Passing integers by reference?" for more details.

You can either return a value that you then assign to your variable, like so:

a = 5
def do_something(value)
    return 1 #this could be more complicated and depend on the value passed in
end
a = do_something(a)

or you could wrap your value in an object such as a Hash and have it updated that way.

a = {:value => 5}
def do_something(dict)
  dict[:value] = 1
end
do_something(a) #now a[:value] is 1 outside the function

Hope this helps.

When I was building a game I had the same problem you have. There was a numeric score that represented how many zombies you've killed and I needed to manually keep it in sync between Player (that incremented the score), ScoreBar and ScoreScreen (that displayed the score). The solution I've found was creating a separate class for the score that will wrap the value and mutate it:

class Score
  def initialize(value = 0)
    @value = value
  end

  def increment
    @value += 1
  end

  def to_i
    @value
  end

  def to_s
    @value.to_s
  end
end