• Descriptions that you should have to understand a Design Pattern
• Normally PD is described by UML. Here’s an example. Lines are some kind of relationship. boxes represent classes or interfaces and include important fields.

Apply a Pattern

Practice

• Do a coding exercise or kata
• Write tests to verify that you understand
• Repeat several times with variations
• Practice on real code in a separate branch - then delete it

In Real Code

• Follow Refactoring Fundamentals course
• Make sure you have test coverage
• Do the work in a separate branch - use a pull request or similar tool to merge
• Verify behavior is consistent after completing the refactoring
• Be prepared to delete and start over if the result isn’t better than the original

What is a Pattern?

• It solves a problem
• It is a proven concept
• The solution is not obvious
• It describes a relationship
• It has a significant human component