Refactoring to Design Patterns (phpDay 2009)

Refactoring to Design Pa0erns Simone Carle5

phpDay 2009 – May 15‐16, 2009 – Verona, Italy h0p://grusp.it ‐ h0p://phpday.it ‐ h0p://joind.in/event/view/34

About Me

•  Technical Manager in Altura Labs •  Addicted to Agile Development

•  Fallen in love with Development Best Prac=ces

•  Passionate about Object Oriented Programming

phpDay 2009 – 15 e 16 Maggio Verona, Italy

Designing object oriented soKware is hard, and designing reusable object‐oriented soKware is

even harder.

Design Pa*erns (GoF)


EvoluRon

Maintainability


Maintainability

Long project lifecycle


Maintainability


Scalability


Maintainability


Scalability

Flexibility


… and we need it for yesterday!


Design for Changes

The key to maximizing reuse lies in an=cipa=ng new requirements and changes to exis=ng

requirements, and design your system so that they can evolve accordingly.

Design Pa*erns (GoF)


Bad Smell

hVp://www.codinghorror.com/blog/archives/000589.html

D.R.Y.

Don’t repeat yourself

K.I.S.S.

Keep it Simple, Stupid

Y.A.G.N.I.

You Ain't Gonna Need It

Over‐Engineering


Under‐Engineering


Refactoring

What is Refactoring?

Refactoring is a disciplined technique for restructuring an exis=ng body of code, altering

its internal structure without changing its external behavior.

Mar2n Fowler


Why?

•  Improve readability •  Improve maintainability

•  Gain a beVer understanding of code


How?

•  Small steps •  Con=nuous •  Don’t add features •  … or bugs •  Have a good knowledge of the code


Design Pa0erns

Design PaVerns describe simple and elegant solu=ons to specific problems in object

oriented soKware design.


Each paVerns describes a problem which occurs over and over again in our environment, and then describes the core of the solu=on to that problem, in such a way that you can use this

solu=on a million =mes over.

Christopher Alexander


Context

Problem

Solu=on


A word of warning

Ideally when the appropriate problem comes along, you should trigger the design paVern

and your problem is solved.

Russ Olsen, Design Pa*erns in Ruby


Design Pa0erns by Purpose

•  Crea=onal PaVerns •  Structural PaVerns •  Behavioral PaVerns

•  Concurrency PaVerns •  Architectural PaVerns


There is a natural rela=on between paVerns and refactorings.

PaVerns are where you want to be,

refactorings are ways to get there

from somewhere else.

Mar2n Fowler


TesRng

TesRng

performance

integra=on

func=onal

unit


Test Driven Development


Tes=ng

Refactoring

Design PaVerns


Refactoring to Design Pa0erns

Observer

Observer

The Observer paVern defines dependency between objects so that when one object change state, all its dependents are no=fied

and updated automa=cally


Observer

Post

CacheSweeper Logger EmailNo=fier


Observer

Post


$post‐>=tle = “foo”; $post‐>save();


Observer

Post


$post‐>=tle = “foo”; $post‐>save();

aKer_save() aKer_save() aKer_save()


Observer

Post


$post‐>delete();


Observer

Post


aKer_delete() aKer_delete()

$post‐>delete();


Code Time

Strategy

Strategy

function doSomething($even, $odd){ if ($even == "secret") { if ($odd == "other secret") { return 1; } else if ("pizza" == "good") { return "Yes it is!"; } } else if ($odd != $even) { return "yeah, they are"; } else { return "I'm getting crazy"; }}


Strategy

method($params){

// complex logic// conditional strategy

}


Strategy

Strategy 1 Strategy 2 Strategy 3

method($params){

$s = new Strategy();$s->method($params);

}

$s = new Strategy()

$s->method($params);


Code Time

QuesRons?


License This presenta=on is published under the AVribu=on‐Share Alike Unported Crea=ve Commons License.

You are free:

•  to Share — to copy, distribute and transmit the work

•  to Remix — to adapt the work

Under the following condi=ons:

•  A0ribuRon — You must aVribute the work in the manner specified by the author or licensor (but not in any way that suggests that they endorse you or your use of the work).

•  Share Alike — If you alter, transform, or build upon this work, you may distribute the resul=ng work only under the same, similar or a compa=ble license.

Visit hVp://crea=vecommons.org/licenses/by‐sa/3.0/ for more details.


Thank you!

Slides will be available at www.simonecarleq.com

www.slideshare.net/weppos

Rate this talk at

hVp://joind.in/talk/view/417

Refactoring to Design Patterns (phpDay 2009)

Technology

Transcript of Refactoring to Design Patterns (phpDay 2009)