gistfile1.rb

class Parameter
  attr_accessor :value

  def initialize(value, update)
    @value = value
    @update = update
  end
  def update
    @value = @update.call
  end
  def to_s
    @value.to_s
  end
end

$sim = Hash.new

def val(param)
  $sim[param].value
end

$sim = {
  heatIn: Parameter.new(2, Proc.new {val(:heatIn) + 1}),
  heatOut: Parameter.new(1, Proc.new {val :heatOut}),
  temp: Parameter.new(100, Proc.new {val(:temp) + val(:heatIn) - val(:heatOut)})
}

5.times do |i|
  puts "cycle #{i}"
  $sim.each do |n, p|
    p.update
    puts p
  end
end