Developer Skill Sprint: Refactoring Legacy Code to Design Patterns

Daniele Teti - bittime.it

Tuesday, March 22, 2016

Skill Sprint Replay on Embarcadero YouTube channel: https://www.youtube.com/watch?v=St-8aY5GREc

Refactoring Introduction

Refactoring is a controlled technique for improving the design of an existing code base

• Simplify debug
• Lower code maintenance cost
• Higher ROI (Return on Investment)
• Lower TCO (Total Cost of Ownership)
• Keep developers happy

Design Patterns Introduction

Explains a general design that addresses a recurring design problem in object-oriented systems

• Improve developers discussions
• shared vocabulary
• Speed up the learning process for new team members
• Allow to learn from the others experience
• Simplify debug

Refactoring: The Book

• by Martin Fowler, Don Roberts, William Opdyke, Kent Beck, John Brant
• Publisher: Addison-Wesley Professional
• Release Date: June 1999
• Introduce the refactoring process
• The bulk of the book is around seventy refactorings described in detail
• Several development environments, Delphi included, automate many of the refactorings described in this book. 
• Refactoring has become a full-fledged part of the software development lexicon

Design Patterns: The Book

• by Erich Gamma, Richard Helm, Ralph Johnson and John Vlissides
• Publisher: Addison-Wesley Professional
• Release Date: October 31, 1994
• Introduces the concept of Design Patterns as reusable elements
• Covers the design of object-oriented software
• How to investigate requirements, create solutions and then translate designs into code
• Shows developers how to make practical use of the most significant recent developments
• A summary of UML notation is included

Refactoring to Patterns: The Book

• By Joshua Kerievsky
• Publisher: Addison-Wesley Professional
• Release Date: August 15, 2004
• Refactoring to Patterns is the marriage of refactoring with patterns.
• Suggests that using patterns to improve an existing design is better than using patterns early in a new design.
• This is true whether code is years old or minutes old.

Some Important Code Refactoring Patterns

• Extract Method
• Extract Interface 
• Extract Superclass
• Extract Subclass
• Pull Up Method
• Move Method
• Rename Method
• Replace Inheritance with Delegation
• Replace Conditional with Polymorphism
• Replace Type Code with Subclasses

Refactoring to Patterns

• Chain Constructors
• Replace Multiple Constructors with Factory Methods
• Encapsulate Subclasses with Factory Methods
• Form Creation Class
• Encapsulate Composite with Builder
• Compose Method
• Many others

Learning Resources

• DocWiki
  • Refactoring Code
  • Code Editor 
  • Formatting Source Code
  • Using Bookmarks
  • Using Class Completion
  • Using Code Folding
  • Using Code Insight
  • Using Sync Edit
  • Using Live Templates
  • Creating Template Libraries
  • Recording a Keystroke Macro
  • Code Completion
  • Using To-Do Lists
• bit Time Professionals Training (English/Italian)