How to add an instance of a class into an array of another class (Ruby)-CodePudding

I have two files in my directory, one which is garage.rb & another called car.rb.

car.rb file just holds a car object:

class Car
end

garage.rb file is as follows:

require 'car.rb' #Makes car class accessible in garage.rb

class Garage
  def initialize
    @capacity = []
  end

  attr_accessor :capacity

end

When I make a new instance of a car by calling car = Car.new, how do I put car object in the @capacity array my default?

Essentially, whenever I call car = Car.new, I want car to be put in the @capacity array instantly.

I understand that I could make a function like so:

def add_car_to_garage(car)
  capacity << car
end

But, I want the car to start in the garage when it is created, so I don't want a method to add it to the array, I just want it to automatically start there when the instance of car is created.

Any advice would be appreciated. Thank you.

CodePudding user response：

You can use the ObjectSpace module with each_object method inside your Car class to define method to keep track for each living instances, like this:

class Car

  def self.all
    ObjectSpace.each_object(self).to_a
  end
end

require_relative 'car' # Makes car class accessible in garage.rb 
                                                                 
class Garage                                                     
  def initialize                                                 
    @capacity = Car.all                                          
  end                                                            
                                                                 
  attr_accessor :capacity                                        
end

car1 = Car.new        
car2 = Car.new        
car3 = Car.new        
                      
garage = Garage.new   
                      
print garage.capacity   # => [#<Car:0x0000563fa14128c8>, #<Car:0x0000563fa1412918>, #<Car:0x0000563fa1412990>]

Also note, I have used require_relative to include car.rb class which is in the same directory.

Edit for comment question:

require_relative 'car' # Makes car class accessible in garage.rb 
                                                                 
class Garage                                                     
  def initialize                                                 
  end                                                            
                                                                 
  def capacity                                                   
    Car.all                                                      
  end                                                            
end                                                              
                                                                 
car1 = Car.new                                                   
garage = Garage.new                                              
car2 = Car.new                                                   
                                                                 
print garage.capacity  # => [#<Car:0x000055f5ee49a838>, #<Car:0x000055f5ee49a978>]

Also note, I removed attr_accessor :capacity, since you don't need it in this case.