Decompose Conditional

This is one of the refactorings from Martin Fowler’s book.

Learning Goals

• Describe the refactoring “Decompose Conditional”
• Use refactoring tools to decompose a conditional

Session Outline

• 5 min connect: What is clean & tidy code?
• 5 min concept: Decompose Conditional
• 10 mins demo: TennisGame6, using IDE shortcuts
• 25 min do: Diagram Printer in pairs
• 5 min conclusions: Explain the main idea

Connect - What is clean & tidy code?

Pick the correct items from a list like this:

• Write a comment explaining every line of code
• Instead of duplicating code, extract a method
• Leave unused variables in code comments for future reference
• Use short variable names like a,b,c
• … your own ideas here

The idea is to get them thinking about what makes code good and readable.

Concept - Decompose Conditional

This is one of the refactorings from Martin Fowler’s book, explain what it is and why you might want to do it.

Demo - TennisGame6

TennisGame6 from Tennis Refactoring Kata is designed to have a conditional that is easy to decompose. With your refactoring tools you should be able to do it quite quickly and show a version that is much easier to read and understand.

Exercise - Tennis & DiagramPrinter

Get them first to repeat what you did with TennisGame6. If they are already quite good with their tools then they will also have time to work on DiagramPrinter - use the ‘with_tests’ branch. Ask them to work on decomposing and improving conditional logic in DiagramPrinter.doPrint() and DiagramPhysicalPrinter.doPrint().

Conclusions - explain the main idea

Explain the main idea of ‘Decompose Conditional’.