Refactoring 002 — Extract Method

Find some code snippets that can be grouped and called atomically.

Maximiliano Contieri

Nov 25, 2021

TL;DR: Group your cohesive sentences together

Problems Addressed 😔

Readability
Complexity
Code Reuse

Related Code Smells 💨

Code Smell 03 - Functions Are Too Long

Code Smell 05 - Comment Abusers

Code Smell 18 - Static Functions

Code Smell 22 - Helpers

Code Smell 74 - Empty Lines

Code Smell 78 - Callback Hell

Code Smell 102 - Arrow Code

Code Smell 107 - Variables Reuse

Code Smell 154 - Too Many Variables

Code Smell 169 - Glued Methods

Steps 👣

Move the code fragment to a separate new method
Replace the old code with a call to the recently created method.

Sample Code 📖

Before 🚨

object Ingenuity {
    fun moveFollowingPerseverance() {
        // take Off
        raiseTo(10 feet)

        // move forward to perseverance
        while (distanceToPerseverance() < 5 feet) {
             moveForward()             
         }

        // land
        raiseTo(0 feet)
    }

After 👉

object Ingenuity {   
    // 1. Move the code fragment to a separate new method 
    private fun takeOff() {
        raiseTo(10 feet)
    }

    // 1. Move the code fragment to a separate new method 
    private fun moveForwardToPerseverance() {
       while (distanceToPerseverance() < 5 feet) {
             moveForward()             
         }
    }

    // 1. Move the code fragment to a separate new method 
    private fun land() {
        raiseTo(0 feet)
    }

    fun moveFollowingPerseverance() {
        takeOff()
        // 2. Replace the old code with a call
        // to the recently created method
        moveForwardToPerseverance()
        // 2. Replace the old code with a call 
        // to the recently created method
        land()
        // 2. Replace the old code with a call
        // to the recently created method
    }
}