Avoid Code Duplication! Principles & Patterns

Lars-Erik KindbladSenior Consultant

Blog: kindblad.com

Agenda

Why avoid code duplication?Principles and patterns:

Extract Method Principle Inheritance Principle Execute Around Method Pattern

Why avoid code duplication?

“The way you get programmer productivity is by eliminating the lines of code you have to write” – Steve Jobs

How? Stop duplicating and repeating code! Less Code to Write = Less Code to Maintain = More features delivered = More productive

We normalize databases – should also normalize our codeDRY – Don’t repeat yourself – Single Source of Truth

Extract Method Principle: Example

Duplicated Code

Extract Method Principle: Example

Extract the code to a new method

Extract Method Principle: Example

Refactored to call the new method

Inheritance Principle: Example

Duplicated Code

Inheritance Principle: Example

Refactored to a common base class

Execute Around Method Pattern: Example

Duplicated Code

Execute Around Method Pattern: Example

Refactored to a new execute around method

Execute Around Method Pattern: Example

Refactored to use the new method

Execute Around Method Pattern: Example

Or:

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