Clean Code TipsSeptember 2013

@JuanmaGomeR

How do we code?

It is done when (we think) it is working.

We invest the minimum amount time to get the best

results. Are you sure?

@JuanmaGomeR

@JuanmaGomeR

Smells

Economic smells

● Over 80% of time spent reading code instead of writing it.

● High maintenance cost.● Unmotivated PEOPLE.

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Technical smells

● Classes with 2.000 lines of code● Methods with over 200 lines of

code● Lots of comments trying to

explain what the code is supposed to do

● Duplicated lines of code (Copy & Paste everywhere) @JuanmaGomeR

Why do I have to take care of it?

Because you write it

Every time you write bad code you are being part of

the problem

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Good Practices

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Intention-revealing names

Your classes, methods, functions and attributes

should tell you why they are there for

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Do what you are supposed to do

Each function, method or class only has to contain the

business logic that they declare

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Do what you are supposed to do

If you are writing an user-and-password-checking

method, don’t start a new session in the system, just

check if the user and password are correct

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Don’t Repeat Yourself principle

Don’t clone code, reuse it instead

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Don’t Repeat Yourself principle

Every time you copy & paste code, you are exponentially

rising the probability of having problems in your next

change

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Single responsibility principle

There should be only one possible reason to modify a class, method or whatever

artifact in your project

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Single responsibility principle

They need to have just ONE RESPONSIBILITY each

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Small number of arguments

A small number of arguments per method or function indicates that we are...

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Small number of arguments

… sharing responsibilities

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Small number of arguments

… creating more reusable data structures

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Small number of arguments

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… decreasing the amount of time spent on understanding the purpose of this piece of code

Small artifacts

Small packages, classes, methods, functions are a signal of good code health

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Include comments in complex algorithms only

This way we reduce the “I have found comments that say a different thing that

the code” risk

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Include comments in complex algorithms only

Your code must be readable and understandable by itself

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Tips to achieve this good practices

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… to Puppet@JuanmaGomeR

From G

odzilla...

Set a maximum number of lines of code

Limit the amount of allowed code lines per class, method

and function

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Set a maximum number of lines of code

I.E. A maximum of 10 lines for methods and functions,

100 for classes

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Broken Phone

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Avoid comments

Every time you need to write a comment, read the code

you have written again

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Work in pairs

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Invite people to read your code

Before commiting a line of code, ask your partner for

reading it

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Invite people to read your code

Does he/she understand what it is intended to do?

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Code is free

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If you need to write more classes in order to reuse your

code, DO IT, THEY ARE FREE!

Use more classes

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Lets start a refactoring exercise to put in practices

this principles

Now, do it

@JuanmaGomeR

Is there any volunteer in the room?

Now, do it

@JuanmaGomeR