Refactoring to Design Patterns (phpDay 2009)

Transcript

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

   soKware is even harder. Design Pa*erns (GoF) phpDay 2009 – 15 e 16 Maggio Verona, Italy
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   EvoluRon

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   Maintainability phpDay 2009 – 15 e 16 Maggio Verona, Italy

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   Maintainability Long project lifecycle phpDay 2009 – 15 e 16

   Maggio Verona, Italy
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   Maintainability Long project lifecycle Scalability phpDay 2009 – 15 e

   16 Maggio Verona, Italy
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   Maintainability Long project lifecycle Scalability Flexibility phpDay 2009 – 15

   e 16 Maggio Verona, Italy
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   … and we need it for yesterday! phpDay 2009 –

   15 e 16 Maggio Verona, Italy
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    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) phpDay 2009 – 15 e 16 Maggio Verona, Italy
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    None
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    Bad Smell hVp://www.codinghorror.com/blog/ archives/000589.html

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    D.R.Y. Don’t repeat yourself

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    K.I.S.S. Keep it Simple, Stupid

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    Y.A.G.N.I. You Ain't Gonna Need It

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    Over‐Engineering phpDay 2009 – 15 e 16 Maggio Verona, Italy

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    Under‐Engineering phpDay 2009 – 15 e 16 Maggio Verona, Italy

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    Refactoring

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    phpDay 2009 – 15 e 16 Maggio Verona, Italy

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    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 phpDay 2009 – 15 e 16 Maggio Verona, Italy
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    Why? •  Improve readability •  Improve maintainability •  Gain a

    beVer understanding of code phpDay 2009 – 15 e 16 Maggio Verona, Italy
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    How? •  Small steps •  Con=nuous •  Don’t add features

    •  … or bugs •  Have a good knowledge of the code phpDay 2009 – 15 e 16 Maggio Verona, Italy
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    Design Pa0erns

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

    in object oriented soKware design. phpDay 2009 – 15 e 16 Maggio Verona, Italy
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    phpDay 2009 – 15 e 16 Maggio Verona, Italy

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    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 phpDay 2009 – 15 e 16 Maggio Verona, Italy
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    Context Problem Solu=on phpDay 2009 – 15 e 16 Maggio

    Verona, Italy
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    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 phpDay 2009 – 15 e 16 Maggio Verona, Italy
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    Design Pa0erns by Purpose •  Crea=onal PaVerns •  Structural PaVerns

    •  Behavioral PaVerns •  Concurrency PaVerns •  Architectural PaVerns phpDay 2009 – 15 e 16 Maggio Verona, Italy
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    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 phpDay 2009 – 15 e 16 Maggio Verona, Italy
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    TesRng

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    phpDay 2009 – 15 e 16 Maggio Verona, Italy

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    TesRng performance integra=on func=onal unit phpDay 2009 – 15 e

    16 Maggio Verona, Italy
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    Test Driven Development phpDay 2009 – 15 e 16 Maggio

    Verona, Italy
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    Tes=ng Refactoring Design PaVerns phpDay 2009 – 15 e 16

    Maggio Verona, Italy
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    Refactoring to Design Pa0erns

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    Observer

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    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 phpDay 2009 – 15 e 16 Maggio Verona, Italy
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    Observer Post CacheSweeper Logger EmailNo=fier phpDay 2009 – 15 e

    16 Maggio Verona, Italy
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    Observer Post CacheSweeper Logger EmailNo=fier $post‐>=tle = “foo”; $post‐>save(); phpDay

    2009 – 15 e 16 Maggio Verona, Italy
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    Observer Post CacheSweeper Logger EmailNo=fier $post‐>=tle = “foo”; $post‐>save(); phpDay

    2009 – 15 e 16 Maggio Verona, Italy
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    Observer Post CacheSweeper Logger EmailNo=fier $post‐>=tle = “foo”; $post‐>save(); aKer_save()

    aKer_save() aKer_save() phpDay 2009 – 15 e 16 Maggio Verona, Italy
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    Observer Post CacheSweeper Logger EmailNo=fier $post‐>delete(); phpDay 2009 – 15

    e 16 Maggio Verona, Italy
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    Observer Post CacheSweeper Logger EmailNo=fier $post‐>delete(); phpDay 2009 – 15

    e 16 Maggio Verona, Italy
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    Observer Post CacheSweeper Logger EmailNo=fier aKer_delete() aKer_delete() $post‐>delete(); phpDay 2009

    – 15 e 16 Maggio Verona, Italy
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    Code Time

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    Strategy

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    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 != $even) { return "yeah, they are"; } else { return "I'm getting crazy"; } } phpDay 2009 – 15 e 16 Maggio Verona, Italy
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    Strategy method($params) { // complex logic // conditional strategy }

    phpDay 2009 – 15 e 16 Maggio Verona, Italy
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    Strategy Strategy 1 Strategy 2 Strategy 3 method($params) { $s

    = new Strategy(); $s->method($params); } $s = new Strategy() $s->method($params); phpDay 2009 – 15 e 16 Maggio Verona, Italy
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    Code Time

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    QuesRons? phpDay 2009 – 15 e 16 Maggio Verona, Italy

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    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. phpDay 2009 – 15 e 16 Maggio Verona, Italy
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    Thank you! Slides will be available at www.simonecarleq.com www.slideshare.net/weppos Rate

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