Object Relations Code Challenge - DriveIn

For this challenge, we will be working with a drive-in movie domain.

We have three models: DriveIn, MovieScreen, and Car.

For this challenge, a DriveIn has many MovieScreens, a MovieScreen has many Cars, and a Car belongs to a MovieScreen.

A DriveIn has many Cars through its MovieScreens. A Car is only at one DriveIn.

Note: You should draw your domain on paper or on a whiteboard before you start coding. Remember to identify a single source of truth for your data.

Topics

• Classes and Instances
• Class and Instance Methods
• Variable Scope
• Object Relationships
• Arrays and Array Methods

Instructions

To get started, run bundle install while inside of this directory.

Build out all of the methods listed in the deliverables. The methods are listed in a suggested order, but you can feel free to tackle the ones you think are easiest. Be careful: some of the later methods rely on earlier ones.

Remember! This code challenge does not have tests. You cannot run rspec and you cannot run learn. You'll need to create your own sample instances so that you can try out your code on your own. Make sure your associations and methods work in the console before submitting.

We've provided you with a tool that you can use to test your code. To use it, run ruby tools/console.rb from the command line. This will start a pry session with your classes defined. You can test out the methods that you write here. You can add code to the tools/console.rb file to define variables and create sample instances of your objects.

Writing error-free code is more important than completing all of the deliverables listed - prioritize writing methods that work over writing more methods that don't work. You should test your code in the console as you write.

Similarly, messy code that works is better than clean code that doesn't. First, prioritize getting things working. Then, if there is time at the end, refactor your code to adhere to best practices. Examples of best practices might be to use higher-level array methods such as map, select, and find when appropriate in place of each, or, when you encounter duplicated logic, to extract it into a shared helper method.

Before you submit! Save and run your code to verify that it works as you expect. If you have any methods that are not working yet, feel free to leave comments describing your progress.

Deliverables

Write the following methods in the classes in the files provided. Feel free to build out any helper methods if needed.

Deliverables use the notation # for instance methods, and . for class methods.

Some of the methods listed are provided to you in the starter code. You should check that they work correctly, and that you understand them.

Initializers, Readers, and Writers

DriveIn

• DriveIn#initialize(name)
  • A drive-in should be initialized with a name as a string.
  • The name cannot be changed after the drive-in is initialized.
• DriveIn#name
  • should return the name of the DriveIn

MovieScreen

• MovieScreen#initialize(movie_title, capacity, drive_in)
  • A movie screen should be initialized with a movie title as a string, capacity (as an integer), and a drive_in object.
  • The movie title, capacity, and drive in cannot be changed after the MovieScreen is initialized.
• MovieScreen#movie_title
  • should return the movie title
• MovieScreen#capacity
  • should return the MovieScreen's capacity
• MovieScreen#drive_in
  • should return the DriveIn associated with this MovieScreen
• MovieScreen.all_screens
  • Returns an array of all movie screens that have been created.

Car

• Car#initialize(passenger_count)
  • A car should be initialized with a passenger_count (as an integer).
  • the passenger count can be changed after the Car is initialized
• Car#passenger_count
  • Returns the number of passengers in the car.
• Car.all
  • Returns an array of all car instances that have been created.

Object Relationship Methods

Car

• Car#current_movie_screen
  • Returns the current movie screen that a particular car is associated with.
• Car#current_movie_screen=
  • Assigns a movie screen object to a particular car to indicate which movie screen that car is currently at.
  • Note: this will happen after a car has already been created.

MovieScreen

• MovieScreen#cars
  • Returns an array of all cars currently at this movie screen.

DriveIn

• DriveIn#screens
  • Returns an array of all movie screens at this drive-in.

Aggregate Methods

MovieScreen

• MovieScreen#number_of_viewers
  • Returns the total number of passengers viewing the movie, from all the cars currently at this movie screen
• MovieScreen#at_capacity?
  • Returns a boolean. If the number of cars at this movie screen is equal to or above the capacity of the movie screen, returns true. Otherwise, returns false.
• MovieScreen#available_spots
  • Returns the number of spots for cars available at this movie screen. This should be the capacity minus the number of cars currently at this movie screen.
• MovieScreen#add_car(car)
  • Takes in a Car instance as the argument
  • Depending on the available capacity of the movie screen, associates the Car with this movie screen.
    • If the movie screen is not at capacity, updates the car's current movie screen and returns the string "Enjoy!".
    • If the movie screen is at capacity, it should return the string "Sold Out!", and should not associate the car to the movie screen.

DriveIn

• DriveIn#whats_playing
  • Returns an array of all the names of the movies playing at the movie screens at this drive-in.
• DriveIn#full_house?
  • Returns true if all movie screens at this drive-in are at capacity.

Rubric

You can find the rubric for this assessment here.