Clean Code Lecture Session I

Introduction to Clean Code &Names part I

By Niko Adrianus Yuwono

It is not the language that makes programs appear

simple. It is the programmer that make the language

appear simple

Dave Thomas says code can be described as a clean code when :

1. The code is simple & direct. 2. Can be read, and enhanced by a developer

other thank it’s original author. 3. It has meaningful names. 4. It provides one way rather than many ways

for doing one thing.5. It has minimal dependencies, which are

explicitly defined, and provides a clear and minimal API.

What is Clean Code?

Code is the core of the application. Code represents the details of the requirement. Code is really the language in which we ultimately express the requirements.

If you’ve been in a team project you have probably been significantly slowed down by someone else’s messy code.

Why Clean Code?

Only knowing how to recognize clean code from dirty code is not enough because it’s doesn’t mean we know how to write clean code.

In this lecture we’ll do some exercises to help us to know how to write clean code and make it a habbit.

What should we do?

Names are everywhere in software. We name our variables, our functions, our arguments, classes, and packages. We name our source files and the directories that contain them.

Because we do so much of it, we’d better do it well. What follows are some simple rules for creating good names.

Meaningful Names

The name of a variable, function, or class, should answer all the big questions. It should tell you why it exists, what it does, and how it is used. If a name requires a comment, then the name does not reveal its intent.

Intention-Revealing Names

int e; // total number of employee

The name e reveals nothing. We should choose a name that specifies what is being measured and the unit of that measurement:

Another example

Cont’d

int totalNumberOfEmployee;

int daysSinceLastLogin;String employeeEmailAddress

This is an example of dirty code

Example

public ArrayList<int[]> getThem() {

ArrayList<int[]> ArrayList1 = new ArrayList<int[]>();for (int[] x : globalArrayList)

if (x[0] == 4) ArrayList1.add(x);

return ArrayList1;}

Why is it a dirty code? Because we cannot comprehend what’s the author want to express in his code. The code is very implicit. We must ask the author some question like :

1. What kinds of things are in globalArrayList?2. What is the significance of the 0th

subscript of an item in globalArrayList?3. What is the significance of the value 4?4. How would I use the list being returned?

Cont’d

We can rewrite the dirty code to this one:

Cont’d

public ArrayList<Member> getDietitianMember() {

ArrayList<Member> dietitianMembersList = new ArrayList<Member>();for (Member member : allMemberList)

if (member[TYPE] == DIETITIAN) dietitianMembersList.add(member);

return dietitianMembersList;}

Cont’d

public ArrayList<Member> getDietitianMember() {

ArrayList<Member> dietitianMembersList = new ArrayList<Member>();for (Member member : allMemberList)

if (member.isDietitian()) dietitianMembersList.add(x);

return dietitianMembersList;}

We should avoid words whose entrenched meanings vary from our intended meaning.

For example do not refer to a grouping of accounts as an accountList unless it’s actually a List.

Beware of using names which vary in small ways. How long does it take to spot the subtle difference between a XYZControllerForEfficientHandlingOfStrings in one module and, somewhere a little more distant, XYZControllerForEfficientStorageOfStrings?

Avoid Disinformation

Usually when we can’t use the same name to refer to two different things in the same scope, we might be tempted to change one name in an bad way like a1 and a2.

It is not sufficient to add number series, even though the compiler is satisfied. If names must be different, then they should also mean something different.

Make Meaningful Distinctions

This function is an example of a noninformative function

The use of variable a1 and a2 didn’t give us clue what is the author intention.

Example

public static void copyChars(char a1[], char a2[]) {

for (int i = 0; i < a1.length; i++) {a2[i] = a1[i];

}

}

Some other example of indistinguishable name :

1. money and moneyAmount2. customer and customerInfo3. accountData and account4. theMessage and message

Cont’d