Episode 6 Half-Eagle

[moserrya]

Did this using Postgres (not sure if that was the intent). Rather make Automobile inherit from Vehicle if you already have it inheriting from ActiveRecord will all of the attendant naming conventions :'(

Cannot for the life of me figure out how to return vehicle count using a class variable. Let's say I put @@count = 0 inside of the vehicle class - think I want to put @@count += 1 inside of def initialize, but can't do it because of ActiveRecord - get wrong number of arguments (1 for 0). Tried def after_initialize, but this proved useless. Is there some way to make this work?

[jwo]

I'm not sure this is what you meant...

{|vehicle| vehicle.make == "Honda"; vehicle.color == "blue"; vehicle.model == "Accord"}

This will resolve to (assuming it is a blue Honda Accord)

[true; true; true]

But if it was a blue Toyota Accord, it would be:

[false; true; true]

I'll add some code to the main description on better way to do this

[jwo]

Cool that you did it using Postgres -- was not the intent, but sure, why not. From here, going to assume you were not using Postgres; just in memory ruby objects:

If you want to have a count of the number of objects created, then you need to store the vehicles created. Something like this:

class Vehicle
  @@vehicles = []
  def count
    @@vehicles.count
  end
end

class Automobile
  def initialize
    @@vehicles = self
  end
end

Then, you can do:

Vehicles.count

OK, so let's assume you were using Postgres. You have two options:

save the vehicles

Rather than Automobile.new, use Automobile.create. Then ask the database for the count:

Automobile.count
Automobile.where(make: "Honda").where(color: "blue").where(model: "Accord").count

Still track in memory

class Vehicle < ActiveRecord::Base
  @@vehicles = []
  def count
    @@vehicles.count
  end
end

class Automobile < Vehicle

  def after_initialize
    @@vehicles << self
  end
end

[jwo]

Let me know if you have any questions!