wulab · August 6, 2018 10:45 · wulab · Sep 19, 2014
diff --git a/weather_o_rama.rb b/weather_o_rama.rb
 module Subject
  def register_observer()
    raise NotImplementedError
  end

  def remove_observer()
    raise NotImplementedError
  end

  def notify_observers()
    raise NotImplementedError
  end
 end

 module Observer
  def update()
    raise NotImplementedError
  end
 end

 module DisplayElement
  def display()
    raise NotImplementedError
  end

  # UTF-8 encoding table and Unicode characters
  # http://www.utf8-chartable.de/unicode-utf8-table.pl?start=9472&unicodeinhtml=dec
  def box(title, body, width=78)
    lines = []
    lines << "╔%s╗" % ( "[ #{title} ]".center(width, "═") )
    lines << "║%s║" % ( "░" * width                       )
    lines << "║%s║" % ( " #{body} ".center(width, "░")    )
    lines << "║%s║" % ( "░" * width                       )
    lines << "╚%s╝" % ( "═" * width                       )
    lines.join("\n")
  end
 end

 ###

 class WeatherData
  include Subject

  attr_reader :temperature, :humidity, :pressure
  attr_reader :observers

  def initialize
    @observers = []
  end

  def register_observer(observer)
    observers.push(observer)
  end

  def remove_observer(observer)
    observers.delete(observer)
  end

  def notify_observers()
    observers.each(&:update)
  end

  def measurements_changed()
    notify_observers()
  end

  def set_measurements(temperature, humidity, pressure)
    @temperature = temperature
    @humidity    = humidity
    @pressure    = pressure
    measurements_changed()
  end
 end

 class CurrentConditionsDisplay
  include Observer
  include DisplayElement

  attr_reader :temperature, :humidity
  attr_reader :weather_data

  def initialize(weather_data)
    @weather_data = weather_data
    @weather_data.register_observer(self)
  end

  def update()
    @temperature = weather_data.temperature
    @humidity    = weather_data.humidity
    display()
  end

  def display()
    title = "Current Conditions"
    body  = "#{temperature} F degrees and #{humidity}% humidity"
    puts box(title, body)
  end
 end

 class ForecastDisplay
  include Observer
  include DisplayElement

  attr_reader :current_pressure, :last_pressure
  attr_reader :weather_data

  def initialize(weather_data)
    @current_pressure = 29.92
    @weather_data     = weather_data
    @weather_data.register_observer(self)
  end

  def update()
    @last_pressure    = current_pressure
    @current_pressure = weather_data.pressure
    display()
  end

  def display()
    title = "Forecast"
    body  = if current_pressure > last_pressure
              "Improving weather on the way!"
            elsif current_pressure < last_pressure
              "Watch out for cooler, rainy weather"
            else
              "More of the same"
            end
    puts box(title, body)
  end
 end

 class StatisticsDisplay
  include Observer
  include DisplayElement

  attr_reader :max_temp, :min_temp, :temp_sum, :num_readings
  attr_reader :weather_data

  def initialize(weather_data)
    @max_temp     = 0
    @min_temp     = 200
    @temp_sum     = 0
    @num_readings = 0
    @weather_data = weather_data
    @weather_data.register_observer(self)
  end

  def update()
    @temp_sum     += weather_data.temperature
    @num_readings += 1

    if weather_data.temperature > @max_temp
      @max_temp = weather_data.temperature
    end

    if weather_data.temperature < @min_temp
      @min_temp = weather_data.temperature
    end

    display()
  end

  def display()
    title = "Statistics"
    body  = "Avg/Max/Min temperature = %s/%s/%s"
    body  = body % [temp_sum/num_readings, max_temp, min_temp]
    puts box(title, body)
  end
 end

 class HeatIndexDisplay
  include Observer
  include DisplayElement

  attr_reader :heat_index
  attr_reader :weather_data

  def initialize(weather_data)
    @weather_data = weather_data
    @weather_data.register_observer(self)
  end

  def update()
    @heat_index = compute_heat_index(
                    weather_data.temperature,
                    weather_data.humidity
                  )
    display()
  end

  # The Heat Index Equation
  # http://www.hpc.ncep.noaa.gov/html/heatindex_equation.shtml
  def compute_heat_index(t, rh)
    -42.379 + 2.04901523*t + 10.14333127*rh - 0.22475541*t*rh -
      0.00683783*t*t - 0.05481717*rh*rh + 0.00122874*t*t*rh +
      0.00085282*t*rh*rh - 0.00000199*t*t*rh*rh
  end

  def display()
    title = "Heat Index"
    body  = "Heat index is %.2f" % @heat_index
    puts box(title, body)
  end
 end

 ###

 class WeatherStation
  def self.start()
    weather_data = WeatherData.new

    current_display    = CurrentConditionsDisplay.new(weather_data)
    forecase_display   = ForecastDisplay.new(weather_data)
    statistics_display = StatisticsDisplay.new(weather_data)
    heat_display       = HeatIndexDisplay.new(weather_data)

    weather_data.set_measurements(80, 65, 30.4)
    weather_data.set_measurements(82, 70, 29.2)
    weather_data.set_measurements(78, 90, 29.2)
  end
 end

 if $0 == __FILE__
  WeatherStation.start()
 end
	module Subject
	def register_observer()
	raise NotImplementedError
	end

	def remove_observer()
	raise NotImplementedError
	end

	def notify_observers()
	raise NotImplementedError
	end
	end

	module Observer
	def update()
	raise NotImplementedError
	end
	end

	module DisplayElement
	def display()
	raise NotImplementedError
	end

	# UTF-8 encoding table and Unicode characters
	# http://www.utf8-chartable.de/unicode-utf8-table.pl?start=9472&unicodeinhtml=dec
	def box(title, body, width=78)
	lines = []
	lines << "╔%s╗" % ( "[ #{title} ]".center(width, "═") )
	lines << "║%s║" % ( "░" * width )
	lines << "║%s║" % ( " #{body} ".center(width, "░") )
	lines << "║%s║" % ( "░" * width )
	lines << "╚%s╝" % ( "═" * width )
	lines.join("\n")
	end
	end

	###

	class WeatherData
	include Subject

	attr_reader :temperature, :humidity, :pressure
	attr_reader :observers

	def initialize
	@observers = []
	end

	def register_observer(observer)
	observers.push(observer)
	end

	def remove_observer(observer)
	observers.delete(observer)
	end

	def notify_observers()
	observers.each(&:update)
	end

	def measurements_changed()
	notify_observers()
	end

	def set_measurements(temperature, humidity, pressure)
	@temperature = temperature
	@humidity = humidity
	@pressure = pressure
	measurements_changed()
	end
	end

	class CurrentConditionsDisplay
	include Observer
	include DisplayElement

	attr_reader :temperature, :humidity
	attr_reader :weather_data

	def initialize(weather_data)
	@weather_data = weather_data
	@weather_data.register_observer(self)
	end

	def update()
	@temperature = weather_data.temperature
	@humidity = weather_data.humidity
	display()
	end

	def display()
	title = "Current Conditions"
	body = "#{temperature} F degrees and #{humidity}% humidity"
	puts box(title, body)
	end
	end

	class ForecastDisplay
	include Observer
	include DisplayElement

	attr_reader :current_pressure, :last_pressure
	attr_reader :weather_data

	def initialize(weather_data)
	@current_pressure = 29.92
	@weather_data = weather_data
	@weather_data.register_observer(self)
	end

	def update()
	@last_pressure = current_pressure
	@current_pressure = weather_data.pressure
	display()
	end

	def display()
	title = "Forecast"
	body = if current_pressure > last_pressure
	"Improving weather on the way!"
	elsif current_pressure < last_pressure
	"Watch out for cooler, rainy weather"
	else
	"More of the same"
	end
	puts box(title, body)
	end
	end

	class StatisticsDisplay
	include Observer
	include DisplayElement

	attr_reader :max_temp, :min_temp, :temp_sum, :num_readings
	attr_reader :weather_data

	def initialize(weather_data)
	@max_temp = 0
	@min_temp = 200
	@temp_sum = 0
	@num_readings = 0
	@weather_data = weather_data
	@weather_data.register_observer(self)
	end

	def update()
	@temp_sum += weather_data.temperature
	@num_readings += 1

	if weather_data.temperature > @max_temp
	@max_temp = weather_data.temperature
	end

	if weather_data.temperature < @min_temp
	@min_temp = weather_data.temperature
	end

	display()
	end

	def display()
	title = "Statistics"
	body = "Avg/Max/Min temperature = %s/%s/%s"
	body = body % [temp_sum/num_readings, max_temp, min_temp]
	puts box(title, body)
	end
	end

	class HeatIndexDisplay
	include Observer
	include DisplayElement

	attr_reader :heat_index
	attr_reader :weather_data

	def initialize(weather_data)
	@weather_data = weather_data
	@weather_data.register_observer(self)
	end

	def update()
	@heat_index = compute_heat_index(
	weather_data.temperature,
	weather_data.humidity
	)
	display()
	end

	# The Heat Index Equation
	# http://www.hpc.ncep.noaa.gov/html/heatindex_equation.shtml
	def compute_heat_index(t, rh)
	-42.379 + 2.04901523t + 10.14333127rh - 0.22475541trh -
	0.00683783tt - 0.05481717rhrh + 0.00122874tt*rh +
	0.00085282trhrh - 0.00000199ttrh*rh
	end

	def display()
	title = "Heat Index"
	body = "Heat index is %.2f" % @heat_index
	puts box(title, body)
	end
	end

	###

	class WeatherStation
	def self.start()
	weather_data = WeatherData.new

	current_display = CurrentConditionsDisplay.new(weather_data)
	forecase_display = ForecastDisplay.new(weather_data)
	statistics_display = StatisticsDisplay.new(weather_data)
	heat_display = HeatIndexDisplay.new(weather_data)

	weather_data.set_measurements(80, 65, 30.4)
	weather_data.set_measurements(82, 70, 29.2)
	weather_data.set_measurements(78, 90, 29.2)
	end
	end

	if $0 == __FILE__
	WeatherStation.start()
	end