ScotRuby 2011 - Charity tutorial Excercise with bindings

binding_exercise.rb

def counter(start=0, increment=1)
  count = nil
  Proc.new do
    count = count ? count+increment : start
  end
end

result = counter(2,3)

puts result.call #2
puts result.call #5
puts result.call #8

puts
result = counter(2,4)

puts result.call #2
puts result.call #6
puts result.call #10

The original solution didn't work because the count was not reset every time we call the method counter(x,y).
It's also not necessary to use instance variables because we are using the binding.