Kent Beck

Martin Fowler

@martinfowler

@KentBeck

Sandi Metz

Katrina Owen

@kytrinyx

@sandimetz

Refactoring

ri-fak-tər-iŋ

(n)

How‽

But

If it ain't broke,

don't fix it.

Is it open for the new requirement?

Is it really open for the new requirement?

Is it really open for the new requirement?

Is it really open for the new requirement?

Primitive Obsession

Primitive Obsession

Primitive Obsession

Recipes

Replace Primitive with Object

• Create a simple value class with a getter
• Run static checks
• Change the setting code to create an instance of the value class
• Run tests
• Consider applying "change reference to value" or "change value to reference"

Replace Conditional with Polymorphism

• Create classes for polymorphic behavior
• Create a factory function to return the correct instance
• Use the factory function in calling code
• Move the conditional to the parent class
• Override each successive leg of the conditional
• Replace the parent class conditional

Takeaways

Now Easy

• getting starting without knowing the end state
• stopping and shipping before reaching the end state

Important, Still Hard

• running tests quickly
• trusting your coverage
• working with QAs
• refactoring Rails magic methods
• finding all callers of a method

Running Tests Quickly

• set up guard and spring
• small objects
• decoupled from ActiveRecord

Trusting Your Coverage

• test more
• consider in-production tests
• science experiments

Trusting Your Coverage

Working with QAs

• talk about regression tests
• talk about development practices

Refactoring Rails Magic

• decouple where you can
• use magic when it makes sense

Finding All Callers

• use descriptive names
• don't get fancy with dynamic send
• consider deprecating, not deleting

Read These

Practice

Write the simplest thing that you need today;