Post on 09-May-2015
description
Revisiting Refactoring
Learning From the Past
Improving the Future
What We Will Cover What is a Refactor What is a Refuctor What are Code Smells What are Code Smiles How does this change what we do
Defining Refactoring
• Code refactoring is the process of changing a computer program's internal structure without modifying its external functional behavior or existing functionality
• improve internal non-functional properties of the software
• improve code readability
• to simplify code
Observations About Refactoring
• Refactoring improves the design of software
– without refactoring, a design will “decay” as people make changes to a software system
• Refactoring makes software easier to understand
– because structure is improved, duplicated code is eliminated, etc.
• Refactoring promotes a deep understanding of the code at hand by tearing it apart and putting it back together again
What We Will Cover
What is a Refactor
What is a Refuctor
What are Code Smells
What are Code Smiles
How does this change what we do
Defining Refuctoring
• Refuctoring is the process of taking a well-designed piece of code and, through a series of small, reversible changes, making it completely unmaintainable by anybody except yourself.
• Often occurs when refactoring is not disciplined
• Occurs when changes are made at the last minute
A Sampling of Refuctors
• Inconsistent Naming Conventions
• Module Gravity Well
• Useless prefixes / suffixes “Pig Latin”
• Reusing names
• Often introduced accidentally in a rush
What We Will Cover
What is a Refactor
What is a Refuctor
What are Code Smells
What are Code Smiles
How does this change what we do
Defining Code Smells
• A Code Smell is a hint that something has gone wrong somewhere in your code
• A Code Smell is a hint that something might be wrong, not a certainty.
• Calling something a CodeSmell is not an attack; it's simply a sign that a closer look is warranted.
A List of Code Smells
• Duplicate Code
• Large Method
• Marge Class
• Inappropriate Intimacy
• Feature Envy
• Switch Statements
• Comments
Observations About Code Smells
• Smells are guidelines
• Smells should not be dogmatic
• Smells should introduce a sense of humor to code reviews
• Code smells have associated Refactors to address specific smells
What We Will Cover
What is a Refactor
What is a Refuctor
What are Code Smells
What are Code Smiles
How does this change what we do
Defining Code Smiles
• A code "smile" is some aspect of the code that makes other developers smile when they have to maintain it.
• Code Smiles add up to code that is easily maintained
A List of Code Smiles
• Common sense naming conventions
• Cohesive and loosely coupled modules
• Elegant abstractions
• Lack of duplication
• A close resemblance to the application domain
Observations About Code Smiles
• Code smiles do not happen by accident
• Code full of Smiles can deteriorate without careful attention
• Code smiles may also require supporting documentation or one on one training
What We Will Cover
What is a Refactor
What is a Refuctor
What are Code Smells
What are Code Smiles
How does this change what we do
Defining Prefactoring
• Simple steps to take to prevent common problems before they arise
• Conduct “Lessons Learned” meetings from previous projects
• Identify common problems
• Take steps at every stage to avoid issues known to cause problems in the past
Towards a Catalog of Prefactors
• Identify a recurring issue
• Define a preventative measure
• Verify that the prevention is being followed
• Verify that the recurring issue is reduced
• Refine the preventative measure
Sample Prefactoring
• Inappropriate Intimacy
• Object model not resembling Business Model
• Separation By Interfaces
• Read code aloud to customers
Where to get More Information
• http://www.refactoring.com/catalog/index.html
• http://www.waterfall2006.com/gorman.html
• http://www.simple-talk.com/dotnet/.net-framework/code-deodorants-for-code-smells/
• http://www.simple-talk.com/author/nick-harrison/