class_objects_instance_methods_challenge.rb

class Continent 
    attr_reader :countries, :name
    @@continents = 0
    @@continent_objects = []

    def self.num_of_continents 
        return @@continents
    end
    
    def self.print_num_of_continents
        return "You have created #{@@continents} #{@@continents < 2 ? "continent" : "continents"}"
    end 

    def self.print_names_of_continent_objects
        if @@continents < 1 
            return "You have no continent objects yet!"
        else 
            @@continent_objects.each_with_index do |continent, index|
                return "#{index + 1}) #{continent.name}"
            end 
        end 
    end 

    def initialize(name)
        @@continents += 1 
        @name = name 
        @countries = []
        @@continent_objects << self
    end

    def add_country(country)
        @countries << country
    end 
end

class Country
    attr_reader :name, :cities
    @@countries = 0 

    def self.num_of_countries 
        return @@countries
    end

    def initialize(name)
        @@countries += 1
        @name = name 
        @cities = [] 
    end
    
    def add_cities(city)
        @cities << city  
    end 
end

class City 
    attr_reader :name
    @@cities = 0 

    def self.num_of_cities 
        return @@cities
    end

    def initialize(name)
        @@cities += 1
        @name = name
    end 
end

# this is the one of the examples that matt likes to see to ensure you understand ruby basics 
# it's a big weird object but you see how different classes link together 
# creating instances that you then call using instance methods to make an object
# first time properly using class variables, useful to count up the total instances that are made