Kent Beck

Martin Fowler

@martinfowler

@KentBeck

Sandi Metz

Katrina Owen

@kytrinyx

@sandimetz

Refactoring

a change made to the internal structure of software

to make it easier to understand and cheaper to modify

without changing its observable behavior.

— Martin Fowler, 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?

Do you know how to make it open?

😎

Is it really open for the new requirement?

Pick the code smell closest to the requirement

Apply a curative recipe for that code smell

😎

Primitive Obsession

using primitive types to represent business objects

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

Good luck!

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

"We can't take the time to refactor,

we have features we have to ship."

If you don't need to change your product

don't change your code

If you need to change your code

make it easy to change

Read These

Practice

We're hiring

Write the simplest thing that you need today;

you can always change it tomorrow