Question

I want to be able to initialize a new Car object and pass it a Person object in the parameters, so it can be saved in that Person’s @cars array. Currently, I take this approach:

person = Person.new("Michael")
car = Car.new("Honda", "Accord")
person.add_car(car)
person.add_car(Car.new("Ford", "Taurus"))
person.add_car(Car.new("Toyota", "Prius"))
person.display

However, I’d like to be able to create a new car instance and pass it the Person object I want it associated with. For example:

person = Person.new("Michael")
Car.new("Honda", "Accord", person)
Car.new("Toyota", "Camry", person)
Car.new("Chevy", "Tahoe", person)
person.display

Is that even possible?

class Person

  attr_accessor :name

  def initialize(name)
    super
    @name = name
    @cars = []
  end

  def display
    puts "#{@name} has #{@cars.length} cars"
    puts "----------------------------"
    @cars.each do |car|
      puts "#{car.make} #{car.model}"
    end
  end

  def add_car(car)
    @cars.push(car)
  end

end 

class Car

  attr_accessor :make, :model

  def initialize(make, model)
    @model = model
    @make = make
  end

  def display
    puts "#{@make} #{@model}"
  end

end

Answer 1

Yes, that is possible, Car#initialize can call methods on its arguments:

class Car
  def initialize(make, model, person = nil)
    @model = model
    @make  = make
    person.add_car(self) if(person)
  end
  #...
end