Cohesion and Coupling is essential in Software Development to improve maintainability, scalability, and realibility. It is a fundamental that every software developers that should know to work with modules in software architecture. In this article, i will explain with some examples using Javascript.
Cohesion
Cohesion is a grouped module that each element inside a module is belong together. The more high level of cohesion, the more good it is. High level of cohesion have a strong readibility and more maintainably code. For example class of users is only allowed to have functions that related to its class, setting email and getting email, we dont need function that out of the class name context like validate email or get email token, because of that things is can be defined on another class like `Users Managers`
1class User {
2 constructor(name, email){
3 this.name = name;
4 this.email = email;
5 }
6
7 getUserEmail() {
8 return this.email;
9 }
10
11 setUserEmail(email) {
12 this.email = email;
13 }
14}the code above is the example of high level of cohesion because it's functions remains of it class
1class User {
2 constructor(name, email){
3 this.name = name;
4 this.email = email;
5 }
6
7 getUserEmail() {
8 return this.email;
9 }
10
11 setUserEmail(email) {
12 this.email = email;
13 }
14
15 //out of context function
16 validateEmail() {
17 //....validate email code
18 }
19}the second one is low level one example, it has validateEmail which is should not being in the `User` class. It's not recomended to write code like the second examples.
Types of Cohesion
There are several types of cohesion, but ill just write down 7 of them
Communicational Cohesion
Communicational cohesion is the third place of cohesion high level.
1function processUserData(user) {
2 validateUser(user);
3 saveUserToDatabase(user);
4 sendConfirmationEmail(user);
5}
6
7function validateUser(user) {
8 if (!user.username || !user.email) {
9 throw new Error("Data user tidak valid");
10 }
11}
12
13function saveUserToDatabase(user) {
14 console.log(`Menyimpan user ${user.username} ke database:`);
15}
16
17function sendConfirmationEmail(user) {
18 console.log(`Mengirim konfirmasi email ke ${user.email}`);
19}
20
21const user = {
22 username: "yasuko_hanaoka",
23 email: "yasuko@gmail.com"
24};
25
26processUserData(user);
27Procedural Cohesion
Procedural cohesion have the same similiarities with sequential, the difference is, procedural doesn't require output from a function become input to another functions. It was on 4 level of high level Cohesion.
1export function startServer(port) {
2 if (!port) {
3 throw new Error("port is must be setted")
4 }
5
6 setPort(port)
7 runServer(port)
8 displayHome()
9}
10
11function setPort(port) {
12 console.log(`setting port to ${port}`)
13 return true
14}
15
16function runServer(port) {
17 console.log(`server is running at port ${port}`)
18}
19
20function displayHome() {
21 console.log("diplaying home...")
22}Coupling
Coupling is.......
Control Coupling
Control coupling is a condition where a module/function controls or determines the execution of another module/function. Usually in the form of flags (conditioning), input parameters and status.
1
2function displayPage(page) {
3 if (page === "home") {
4 displayHome()
5 } else {
6 displayNotFound()
7 }
8}
9
10function displayHome() {
11 console.log("displaying home...")
12}
13
14function displayNotFound() {
15 console.log("displaying not-found....")
16}
17
18displayPage("home")Stamp Coupling
Control coupling is a condition where a module/function controls or determines the execution of another module/function. Usually in the form of flags (conditioning), input parameters and status.
1// struktur data kompleks
2const data = {
3 header: "How to become a software engineer in 3 mins",
4 body: "Lorem ipsum dolor sit amet constrecteur.",
5 thumbnail: "https://cdn.imageasset.net/QIOHsqhWDWsdk",
6 createdAt: "12/08/2022",
7 updatedAt: "12/08/2022"
8}
9
10function displayItem(data) {
11 const { header, body } = data
12 // hanya membutuhkan sebagian data saja
13 return {
14 header,
15 body
16 }
17}
18
19displayItem(data)
20