TL;DR: Refactor and extract functions longer than five lines.
Problems 😔
Low cohesion
High coupling
Hard to read
Low reusability
Solutions 😃
1) Refactor
2) Create small objects to handle specific tasks. Unit-test them.
3) Compose methods
Refactorings ⚙️
Refactoring 010 - Extract Method Object
Refactoring 025 - Decompose Regular Expressions
TL;DR: You can break down a complex validation regex into smaller parts to test each part individually and report accurate errors.
Examples
Libraries
Context 💬
When you write a long function, you hide too many details in one place.
You force the reader to hold multiple concepts in mind.
You mix unrelated responsibilities and make the code hard to test.
You create a rigid block that breaks easily when you change it.
Short, focused functions let you read, test, and modify code faster.
Sample Code 📖
Wrong 🚫
<?
function setUpChessBoard() {
$this->placeOnBoard($this->whiteTower);
$this->placeOnBoard($this->whiteKnight);
// A lot more lines
// Empty space to pause definition
$this->placeOnBoard($this->blackTower);
$this->placeOnBoard($this->blackKnight);
// A lot more lines
}Right 👉
<?
function setUpChessBoard() {
$this->placeWhitePieces();
$this->placeBlackPieces();
}Detection 🔍
[X] Automatic
All linters can measure and warn when methods exceed a predefined threshold.
Tags 🏷️
Bloaters
Level 🔋
[X] Beginner
Why the Bijection Is Important 🗺️
A real-world action should map to a clear, concise function.
When you pack many actions into one function, you lose that mapping.
Developers must mentally reconstruct the steps, which slows comprehension and increases errors.
AI Generation 🤖
AI generators often create long functions if you give them vague prompts.
They tend to cram all logic into one place unless you explicitly request modular code.
AI Detection 🥃
AI tools can fix this smell with the right instructions to split code into small, focused functions.
Try Them! 🛠
Remember: AI Assistants make lots of mistakes
Suggested Prompt: Convert it to more declarative
Without Proper Instructions 📵
With Specific Instructions 👩🏫
Conclusion 🏁
Extract long methods into smaller pieces.
Break complex algorithms into parts.
You can also unit test these parts.
Relations 👩❤️💋👨
Code Smell 75 - Comments Inside a Method
Code Smell 206 - Long Ternaries
Code Smell 107 - Variables Reuse
Code Smell 154 - Too Many Variables
Code Smell 83 - Variables Reassignment
More Information 📕
Also Known as
Long Method
Credits 🙏
Photo by Hari Panicker on Unsplash
Programs are meant to be read by humans and only incidentally for computers to execute.
Donald Knuth
This article is part of the CodeSmell Series.
