Using initializing instance as a parameter in other's class instance initialization - ruby

Question

I have this classes (just a simplified example, not real ones)
class Shop
attr_accessor :name, :products
def initialize(name, products_names=%w(apple orange apple cucumber fennel))
self.name = name
self.products = products_names.map {|name| Product.new(self, name)}
end
end
class Product
attr_accessor :shop, :name
def initialize(shop, name)
self.shop = shop
self.name = name
end
def existing_products_count # problem_comes_here
shop.products #i need to process all products initialized for current shop
.select{|p| p.name==name}.size
end
def uniq_code
"#{name}_#{existing_products_count+1}"
end
end
And here is two questions:
Is this a good approach to pass self for Product instance initialization
and
How can i solve my case to process all already existing shop products for new product initialization
Thank you
UPDATE
all i invented for now is (at least it works like i need)
class Shop
attr_accessor :name, :products
def initialize(name, products_names=%w(apple orange apple cucumber fennel))
Product.class_variable_set(:##all, []) # << added
self.name = name
self.products = products_names.map {|name| Product.new(self, name)}
end
end
class Product
attr_accessor :shop, :name
def self.all # << added
##all
end
def initialize(shop, name)
self.shop = shop
self.name = name
self.class.all << self # << added
end
def existing_products_count # problem goes away here
self.class.all.products # << changed
.select{|p| p.name==name}.size
end
def uniq_code
"#{name}_#{existing_products_count+1}"
end
end
but i feel bad about this kind of solution (i don't know why) and will be appreciate for better one

Answer 1

I'm not sure if I understand the question, but here is one interpretation. Note how I've changed the method Product#uniq_code.
class Shop
attr_accessor :name, :products
def initialize(name, products_names=%w(apple orange apple cucumber fennel))
self.name = name
self.products = products_names.map {|name| Product.new(self, name)}
end
end
class Product
attr_accessor :shop, :name
def initialize(shop, name)
self.shop = shop
self.name = name
end
def uniq_code # problem_comes_here
puts "buy #{self.name} #{self.shop.name}"
end
end
Now let's have an example:
at_store = Shop.new("in store", ["bulldozer", "Ducati"])
online = Shop.new("online", ["can opener", "Makita router"])
arr = [at_store, online]
We can do this:
arr.flat_map { |s| s.products }.each { |p| p.send(:uniq_code) }
# buy bulldozer in store
# buy Ducati in store
# buy can opener online
# buy Makita router online
Is this roughly what you were looking for?
Edit: to save the product instances for a given shop instance:
product_instances = at_store.products
#=> [#<Product:0x007f93f984f938
# #shop=#<Shop:0x007f93f984f988 #name="in_store",
# #products=[...]>, #name="bulldozer">,
# #<Product:0x007f93f984f910
# #shop=#<Shop:0x007f93f984f988 #name="in_store",
# #products=[...]>, #name="Ducati">]
for use later:
product_instances.each { |p| p.uniq_code }
# buy bulldozer in_store
# buy Ducati in_store