bar1.lua

-- this version doesn't need prototype.lua

BarGraph = {
  x = 0, y = 20,
  width = 20, height = 100,
  offset = 0,
  update =
    function (self, t)
      self.height = 60 + 40 * math.sin(self.offset * math.pi / 10 + t / 10)
    end
}
BarGraph.new = function(o)
  o = o or {}
  setmetatable(o, self)
  self.__index = self
  return o
end

bars = {}
for i = 1, 10 do
  bars[i] = BarGraph.new{x = 10 * i, offset = i}
end

for t = 1, 10 do
  print("Step " .. t)
  for _, bar in pairs(bars) do
    bar:update(t)
    print(bar.height)
  end
end

bargraphs.lua

--
-- Note: Uses my prototype.lua NewtonScript inheritance model code
-- from lua-cairo-cocoa
--

BarGraph = obj{
  x = 0, y = 0,
  width = 5, height = 10,
  offset = 0,
  update =
    function (self, t)
      self.height = 10 + math.sin(self.offset * math.pi / 10 + t / 10)
    end
}

bars = {}
for i = 1, 10 do
  bars[i] = obj{BarGraph, x = 10 * i, offset = i}
end

for t = 1, 10 do
  print("Step " .. t)
  for _, bar in pairs(bars) do
    bar:update(t)
    print(bar.height)
  end
end