Design Patterns

Introduction to Design Patterns given in 2012 for AC Partners and in 2019 for itenium.

JavaScript

Creating a framework for generating user forms:

npm install

# React
cd JavaScript/impl-react
npm start

# Angular
cd JavaScript/impl-angular
npm start

Tags

• v1-hard-coded: Entire form hardcoded
• v2-from-config: Entire form from configuration
  • PROBLEM: We can now only show an input field wrapped in a .form-group
• v3-more-config-not-dry: Adding more configuration (placeholder & hint)
  • BUG: config.hint should probably also be implemented for secret and toggle? How to keep this DRY?
• v4-going-all-out: Setting up a framework that works with React/Angular and Bootstrap/Foundation

DotNet

1 OpenClosedPrinciple

Example 1-3: Calculating shape area

Adhering to the OpenClosedPrinciple by introducing a PureFabrication (IAreaCalculator) and using Polymorphism instead of type checking.

• Example 1: Calculate area of Circles
• Example 2: A naive implementation when Rectangles are added
• Example 3: Introducing the IAreaCalculator abstraction

Example 4-7: Saving files

Keeping the code DRY:

• Example 4: Code duplication for the different "file saving mechanisms"
• Example 5: A solution with TemplateMethod
• Example 7: A solution with Strategy
• Example 6: Use FactoryMethod on Example 5 to allow each "file saving mechanism" to return custom metadata

2 Patterns

• 1-2.Observer: Examples of Observer: builtin support with event EventHandler<EventArgs>
• 3.Decorator: Example with Streams