marioaquino

require 'forwardable'
 
class Pilotable
  extend Forwardable
  def_delegators :@aircraft, :take_off, :land, :fly_to
 
  def initialize(aircraft)
    @aircraft = aircraft
  end
end

marioaquino

class Drone
  def launch_missiles_at(x, y, z)
  end

  def take_picture_of(x, y, z)
  end

  def take_off
    puts 'taking off...'
  end

marioaquino

#boom!!! a RecordNotFoundError is thrown out of this call
my_user = get_user("user id that will fail") 

marioaquino

my_user_either = get_user("bogus user id")
if my_user_either.value?
  #do whatever with my_user_either.value
else if my_user_either.invalid?
  log.info("Didn't find the user...")
  #do something with my_user_either.error
end

marioaquino

class Either
  attr_reader :value, :error
  def initialize(value: :none, error: :none)
    raise ArgumentError.new("Either a value or an error please, not both") if (value != :none and error != :none)
    raise ArgumentError.new("Either a value or an error please, please give me one") if (value == :none and error == :none)
    @value = value
    @error = error
  end

  def invalid?

marioaquino

class NullProduct < Product
  def cost
    '$0.00'
  end
end

marioaquino

class PerishableProduct < Product
  def shelf_life
    #something
  end
end

marioaquino

class Product
  def cost
    #some value
  end
end

marioaquino

my_user = get_user('some_id_that_may_or_may_not_exist')
if my_user
  #do some stuff
else
 #do the equivalent of what the rescue block above did
end

marioaquino

begin
  my_user = get_user("bogus user id")
rescue RecordNotFoundError
  log.info("Didn't find the user...")
  #return nil? return a "new" user object? 
  #re-raise the error wrapped in a different one? 
  #something else?
end