Introduction

This lesson will continue adding to your object-oriented design skills through a discussion of more of the SOLID and GRASP design principles. The lesson will also look at Design by Contract.

This lesson will look at these principles:

• Controller (GRASP)
• Polymorphism (GRASP)
• Liskov substitution (SOLID)
• Design by contract
• Open/closed (SOLID)
• Pure fabrication (GRASP)

Learning Outcomes

• Identify where the Controller Principle is applicable
• Identify appropriate use of Polymorphism in an object-oriented software design
• Describe the constraints on subclass behavior that are imposed by the Liskov Substitution Principle
• Describe the Design by Contract principle
• Describe why the Open/Closed principle will reduce testing when extending the functionality of an existing class
• Describe how Pure Fabrication can eliminate one or more classes with low cohesion
• Analyze an object-oriented software design for adherence to these design principles.

Study Resources

For your study of this topic, use these resources.

Video Lessons

• DevExpress CTO Messages
  • Liskov Substitution (2:18)
  • Open/Closed (2:28)
• Overview of the SOLID Principles (3:26) from Learning S.O.L.I.D. Programming Principles available through the RIT library gives a general introduction to the principles. The examples are in Python but the principles still hold
• Liskov Substitution (2:33)
• Open/Closed (2:35)
• GRASP Patterns (5:20) from Learning S.O.L.I.D. Programming Principles. Gives a general introduction to the principles. The examples are in Python but the principles still hold.

Web Articles and Blogs

• GRASP patterns
• SOLID vs. GRASP
• The Principles of OOD by Bob Martin (Uncle Bob) the creator of the SOLID set of OO design principles though not the creator of the acronym. There are pages on each one of the principles. Read through these papers for more information about these two SOLID principles.
  • Open/closed
  • Liskov substitution

Books

• For links to work, FIRST LOGIN THROUGH PORTAL HERE ==> GRASP Patterns Patterns in Java, Volume 2 by Mark Grand
  (Available on Skillsoft through the RIT library)
  CHAPTER 4 (only the following):
  • Controller
  • Polymorphism
  • Pure Fabrication
• For links to work, FIRST LOGIN THROUGH PORTAL HERE ==> SOLID Principles in Beginning SOLID Principles and Design Patterns for ASP.NET Developers by Bipin Joshi
  (Available on Skillsoft through the RIT library)
  CHAPTER 2 (only the following):

Wikipedia

• SOLID (object-oriented design)
• GRASP (object-oriented design)
• Open/Closed Principle
• Liskov Substitution Principle
• Controller
• Polymorphism
• Pure Fabrication
• Design by Contract

Class Lecture

• Object-Oriented Design II

ExercisesS

Before-Class Exercises

After-Class Exercises

• Object-oriented design II - team (2 exercise points)
  • Your project team will analyze the design of your term project against the principles discussed in the Object-oriented design II class (Controller, Polymorphism, Liskov Substitution Principle, Open/Closed, Pure Fabrication). Provide your analysis in this Word document and submit it to the Object-oriented design II - team myCourses dropbox in the Team Exercises area by the time indicated on the schedule for your class section. This exercise is worth two exercise points.