Smell your Code! @ Free Dimension

Smell your Code!

Yaser Sulaiman

1 www.free-dimension.com

These slides are based on an internal presentation I gave

@ Free Dimension (FD)

It contained examples from real projects

FD agreed to publish it online under a CC BY-NC-SA license…

after removing, or disguising, the real examples

Disguised examples are marked with

6 δ www.free-dimension.com

Our road map

What? Why? How?

If you can take away only 1 lesson…

Don’t Repeat Yourself!

This rule is so important I have to break it

Don’t Repeat Yourself!

What? Why? How?

Code smells?!

Warning signs

photo by pj_in_oz

www.free-dimension.com

Surface indications of deeper problems

photo by BenChenowethWork

Surface indications of deeper problems

What? Why? How?

The bigger picture

Software Quality

Code Quality

Code Smells

not to scale

Writing HQ code should be the priority

One path to cleaner code goes through code smells

What? Why? How?

Can you smell code?!

photo by lanceball

There’re many code smells

The following smells are just a subset

They’re some of the smells I smelled while working here

Code Smell #1

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The nastiest code smell

DupIicated code DupIicated code DupIicated code DupIicated code DupIicated code DupIicated code DupIicated code DupIicated code DupIicated code DupIicated code DupIicated code DupIicated code DupIicated code DupIicated code DupIicated code DupIicated code DupIicated code DupIicated code

Example #1

BooksController

& NotebooksController

The diff test

ignoring whitespace differences

FD Employees Only!

Example #2

MessagesController

class MessagesController extends AppController { function zebra_inbox() { // inbox code } function zebra_view($id = null) { // view message code } }

class MessagesController extends AppController { function zebra_inbox() { // inbox code } function elephant_inbox() { // inbox code } function zebra_view($id = null) { // view message code } function elephant_view($id = null) { // view message code } }

But then came the penguin, the dolphin, the chimp,…

Refactor!

class MessagesController extends AppController { function zebra_inbox() { $this->setAction('inbox'); } function elephant_inbox() { $this->setAction('inbox'); } function inbox() { // inbox code } function zebra_view($id = null) { $this->setAction('view', $id); } function elephant_view($id = null) { $this->setAction('view', $id); } function view($id = null) { // view message code } }

Added plus: no duplicated views

FD Employees Only!

Code Smell #2

Too many parameters

How many is too many?

Example

(brace your noses!)

public abstract class AProvider { public abstract void AddToFamily(int familyId, string firstName, string sex, string photo, DateTime? birthDate, string birthCountry, string birthCity, bool living, DateTime? deathDate, string country, string city, string email, string homepage, string mobilePhone, string biography, string jobTitle, string maritalStatus, string spouse, int order, int? fatherId); public abstract void UpdateInFamily(int id, int familyId, string firstName, string sex, string photo, DateTime? birthDate, string birthCountry, string birthCity, bool living, DateTime? deathDate, string country, string city, string email, string homepage, string mobilePhone, string biography, string jobTitle, string maritalStatus, string spouse, int order, int? fatherId); }

I misunderstood coupling. My bad!

public abstract class AProvider { public abstract void AddToFamily(Person person); public abstract void UpdateInFamily(Person person); }

The remaining smells have many examples; check the repository

Code Smell #3

Not following a coding convention/standard/style

consistently

Not following a coding convention/standard/style

consistently

The specifics doesn’t really matter; what matters most is consistency

Code Smell #4

// code.CommentOut();

“Commented-out code is an abomination.”—Uncle Bob

photo used with permission of Uncle Bob

Don’t commit commented-out code

Code Smell #5

// This is a comment

redundant

What? Why? How?

Comments should focus on

What? Why? How?

I may have come off as an a$$

My code smells as bad as everyone else’s.. sometimes even worse

But I’m aware of my smells

I try my best to prevent them

I don’t ignore them; I deal with them

I smell my code

You should smell your code too

If you want to sniff more…

more than just code smells

…</presentation> <questions>…

Smell your Code! @ Free Dimension

Technology

Textual Analysis for Code Smell Detection

Code Smell Detection and Identification in Imbalanced

Correctness of Semantic Code Smell Detection Toolsceur-ws.org/Vol-1519/paper3.pdf · Correctness of Semantic Code Smell Detection Tools ... Explicit manual intervention may be needed

When and Why Your Code Starts to Smell Bad (and …mtufano/publications/J3.pdfWhen and Why Your Code Starts to Smell Bad (and Whether the Smells Go Away) Michele Tufano1, Fabio Palomba2;3,

Code Smell Detection in Eclipse - Semantic Scholar · 2017-11-29 · Code Smell Detection in Eclipse Stefan Slinger Thesis Report March 2005 Thesis Supervisor Dr. Ing. L.M.F. Moonen

FOSDEM - Does your configuration code smell?

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Do Code Smell Hamper Novice Programmers?

Code Smell Research: History and Future Directions

Code smell overview

Do They Really Smell Bad? A Study on Developers' Perception of Bad Code Smells

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Machine Learning Techniques for Code Smell Detection: A … · 2019-01-07 · Machine Learning Techniques for Code Smell Detection: A Systematic Literature Review and Meta-Analysis

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How I Learned to Smell Code

When and Why Your Code Starts to Smell Bad (and Whether ...denys/pubs/TSE'17-BadSmells.pdf · This paper is an extension of “When and Why Your Code Starts to Smell Bad” that appeared

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The Scent of a Smell: An Extensive Comparison between ... · information (e.g., textual analysis) for code smell detection have also been recently investigated. Nevertheless, some

Does Your Configuration Code Smell?