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)


http://www.free-dimension.com/

It contained examples from real projects


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


http://creativecommons.org/licenses/by-nc-sa/3.0/





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


16

photo by pj_in_oz

www.free-dimension.com

http://www.flickr.com/photos/pj_in_oz/4045213615/

Surface indications of deeper problems


18

photo by BenChenowethWork


http://www.flickr.com/photos/29317846@N03/2743294768/

Surface indications of deeper problems


What? Why? How?


The bigger picture


Software Quality

Code Quality

Code Smells

23

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?!


30

photo by lanceball


http://www.flickr.com/photos/skimcoat/3850655302

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


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


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


41

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


50

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


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


Code Smell #4


// code.CommentOut();


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

68

photo used with permission of Uncle Bob


Don’t commit commented-out code


Code Smell #5


// This is a comment

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redundant


What? Why? How?

72

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…


82

more than just code smells


http://www.amazon.com/Refactoring-Improving-Design-Existing-Code/dp/0201485672/

http://www.amazon.com/Clean-Code-Handbook-Software-Craftsmanship/dp/0132350882/

http://www.amazon.com/Code-Complete-Practical-Handbook-Construction/dp/0735619670/

http://www.amazon.com/Pragmatic-Programmer-Journeyman-Master/dp/020161622X/

…</presentation> <questions>…


smell your code! @ free dimension

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