This consists of simple examples of the following patterns in Ruby:
In Factory pattern, we create object without exposing the creation logic to client and the client use the same common interface to create new type of object.
We have created a Bike Interface and subclass deriving from it. The BikeFactory class is used to create the object for the each bike.
In the main file, we use to BikeFactory to create each bike object add call the methods in it.
Abstract factory is more over like a factory for factory method. The Abstract Factory is used to create the Factory object for different factories.
We have a Bike Factory which produces variety of bikes. We add a Branded Bike Factory which acts as a Factory for the Bike Factory. Here, we create Bike Factory for each brand which in turns produces each variety of bikes for each brand.
In main, we use Branded Bike Factory to create a Bike Factory for Yamaha and using that Yamaha Bike Factory we create Yamaha Sport Bike.
Template Method as the name suggests, we create a template class with few operation which can be implemented by its child classes.
Here, we create a system for Trip Organizers which lists the details of each package in a certain template. So, we have the template class PackageTemplate which defines the template of the package. By using, this template each package which are its child class details can be presented in that template.
The adapter pattern convert the interface of a class into another interface clients expect. Adapter lets classes work together that couldn’t otherwise because of incompatible interfaces.
Here we have two classes Android and IOS which are incompatible. AndriodIOSAdapter is the adapter class which adapts the Android as the IOS.
The decorator pattern attaches additional responsibilities to an object dynamically. Decorators provide a flexible alternative to subclassing for extending functionality.
Here we explain the decorator with pizza store as an example. Consider we have three pizza Farmhouse, PeppyPanner, SimplePizza in the store and the following add-ons onion, cheesebrust.
In the pizza sotre, we create objects for each pizza and returns the price to be paid. If the user wants the add-ons we need to return the price included the addon amount. So we add a pizza decorator. Using this decorator, we add those addon objects to the pizza object which returns the exat price of the pizza.
Considering you have installed Ruby. Install the Rspec gem using the Gemfile in each pattern with the command - bundle. To install Rspec directly run-- gem install rspec.
To run the program, use the command ruby main.rb To run the test cases, use the command rspec <rspec_filename>