oop_3's Introduction

Delegation

Delegate, delegate, delegate – Russ Olsen, Design Patterns in Ruby

This is a workshop to introduce you to the idea of Object-Oriented delegation.

Learning objectives

Describe "delegation" as "one class telling another class to do something and the other class encapsulating how to do it."
Explain what is meant by the advice "delegate, delegate, delegate".
Implement OOP delegation.

Delegation

In delegation, one class tells another class to do something and the other class encapsulates how to do it.

Look at the company structure code sample for an example of delegation.

Look at this diagram of the company structure code that shows the delegation relationships.

Instructions

This project contains two implementations of a todo list: /terrible and /great.

/terrible implements the features using a poor understanding of the delegate principle. /great implements the users stories using a good understanding of the delegate principle. /great is unfinished.

You job is to finish it.

Running the tests

$ cd terrible/   or   cd great/
$ bundle install
$ rspec

What code should you write?

Port the functionality in /terrible over to /great.
Examine the code and tests in /terrible to find out what functionality to implement.
Continue using the delegate, delegate, delegate approach in /great.
There are a few passing unit tests in /great. You will probably want to add to these.
There are some feature tests in great/spec/feature_spec.rb. These are currently failing. They should pass when you've implemented all the functionality.

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