Prefactoring (Paperback)

Ken Pugh




More often than not, developers will stop a large project in the middle of the build stage to rethink and recode the software design so it's cleaner and more efficient. Known as "refactoring," this process eats up valuable time and money. To help offset refactoring, this book presents a new process called "prefactoring," the premise of which states that you're better off considering the best possible design patterns before you even begin your project.

Prefactoring, in essence, is the art of applying the insights gleaned from previous experience (whether yours or someone else's) when developing software to new projects. Doing so will likely save you from making costly design changes midstream--and maybe even save your job!

This practical, thought-provoking guide details prefactoring guidelines in design, code, and testing, each derived from the lessons of many developers over many years. With these guidelines, you're far more likely to create more readable and maintainable code before you reach the second-guessing stage.

To help communicate the many facets of this process, Prefactoring follows the example of a fictitious client, Sam, as he seeks to create a software system from beginning to implementation. Among the topics covered:

  • General development issues
  • Implementation classes
  • Object-oriented design
  • Creating reports via separation of concerns
  • Associations and states
  • Creating and testing interfaces

If you understand object-oriented design, and you want to save time and money by considering more efficient designs before you begin your project, Prefactoring will show you the way. It won't guarantee that you'll never need to refactor your design or code again, but you're sure to cut down on the amount of refactoring you do.



Table of Contents:


1. Introduction to Prefactoring

     What Is Prefactoring?

     The Three Extremes

     The Guidelines Explored

     The Context for This Book

2. The System in So Many Words

     Meet Sam

     Reinvention Avoidance

     What's in a Name?

     Splitters Versus Lumpers



     Prototypes Are Worth a Thousand Words

3. General Development Issues

     Start with the Big Picture

     Interface Contracts


     Code Communicates

     Consistency Is Simplicity

     A Prefactoring Attitude

     Don't Repeat Yourself

     Documentation of Assumptions and Decisions

     Dealing with Deviations and Errors


     The Spreadsheet Conundrum

     Tools Are Tools-Use Them Wisely

4. Getting the Big Picture

     The Rest of the Story


     The Initial Design

     Global Planning, Local Designing

     Testing Functionality

     Testing Quality


5. Got Class?

     Categories and Classes

     Declaration Versus Execution

     Appropriate Inheritance

     Communicate with Text

     More Than One

6. A Few Words on Classes

     Honor the Class Maxims

     Three Laws of Objects

     Need Determines Class


     One Little Job

     Policy Versus Implementation

     Extreme Naming

     Overloading Functions

7. Getting There

     Where We Are

     Separating Concerns

     Migrating to the New System

8. The First Release

     The Proof Is in the Pudding

     Retrospective Time

     The System as It Stands Now

     Operations Interface

     Abstract Data Types



     Dealing with Deviations and Errors

     A Little Prefactoring

     The First Released Iteration

     Sometimes Practice Does Not Match Theory

     The Rest of the Classes

9. Associations and States

     Sam's New Requirement

     Who's in Charge?

     The State of an Object

10. Interfaces and Adaptation

     The Catalog Search Use Case

     Designing the Interface

     Interface Development

     Interface Testing

     Interface Splitting

     Something Working

11. Zip Codes and Interfaces


     Pass the Buck

     Unwritten Code



     Paradigm Mismatch

12. More Reports

     Fancy Reports

     Change Happens


13. Invoices, Credit Cards, and Discounts

     The Next Step

     The Language of the Client

     Security and Privacy

14. Sam Is Expanding

     The Second Store

     A New Development

     The Third Store

     Goodbye Sam


15. A Printserver Example


     The System

     The Message



     Still More Separation


16. Antispam Example

     The Context

     Spam Checking

     The ReceivingMailServer


     The Full Flow

17. Epilogue

a. Guidelines and Principles

b. Source Code