The SOLID Principles of Software Design

A 2-3 day course for programmers of any experience level that describes the SOLID principles of Object-Oriented software design, and the associated principles of component design.

Audience:

• Programmers of all levels of experience who desire to improve their software design skills._

Duration:

• The two day version is weighted towards lecture and demonstration with a minimum of exercises.
• The three day version shifts the weight towards in-class practice and exercises, withoutdiminishing the lectures and demonstrations.

Outcomes
After this class students will:

• ...understand that modules should have only one reason to change; and be ableto structure systems to minimize the effects of change.
• ...understand that a good software design allows new features to be added withoutchanging existing code.
• ...be able to construct inheritance and polymorphic hierarchies that adhere to a consistentinterface with their users.
• ...understand how to separate interfaces and operations so that low level changes to notpropagate to higher levels.
• ...have a firm grasp on how to manage the dependencies between source code modules suchthat high level policy does not depend upon low level detail.
• ...be able to allocate modules into reusable components.
• ...understand how to separate functionality between components in order to minimize change.
• ...be able to manage the dependencies between components to minimize crosstalk and deployment thrashing.
• ...be able to organize component structures into developable and releasable structures.
• ...understand how to connect components such that changes propagate in the right direction.
• ...know how to allocate classes to components such that high level components do notdepend on low level components.
• ...be familiar with a set of design quality metrics that can be applied to measure the qualityof module and component structures.

Outline

• What goes wrong with Software?
  • Design Smells
    • Rigidity
    • Fragility
    • Inseparability
    • Viscosity
  • Code Smells *

• What is OO?
  • History of OO
  • Dependency Management
  • Dependency Inversion
  • Plug-in Architecture

• Code Rot
  • Example: The Copy Program

• The SOLID Principles
  An in-depth presentation of the principles of class and module design.
  • (SRP) The Single Reponsibility Principle
  • (OCP) The Open-Closed Principle
  • (LSP) The Liskov Substitution Principle
  • (ISP) The Interface Segregation Principle
  • (DIP) The Dependency Inversion Principle

• Component PrinciplesAn in-depth presentation of the principles of component cohesion and coupling.
  • What is a component?
  • Cohesion Principles
    • (REP) The Release Reuse Equivalence Principle
    • (CCP) The Common Closure Principle
    • (CRP) The Common Reuse Principle
  • Coupling Principles
    • (ADP) The Acyclic Dependencies Principle
    • (SDP) The Stable Dependencies Principle
    • (SAP) The Stable Abstractions Principle
  • Design Quality Metrics

• Exercises.
  Several design exercises and demonstrations using UML as time permits.