Mayflower GmbH 2009

Professional RefactoringInternational PHP Conference 2009Spring Edition

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Mayflower GmbH 2009

• Senior Developer / Team Lead at Mayflower GmbH• Reporting and Rating Apps• QA and PHP 5 Migration

consultings• PHP since 1999 (3.0.16)• phpMyFAQ since 2001

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Who are you?

• What are you doing?• What‘s your team size?• Using MVC?• Who‘s using Continous Integration?

• PHPUnit?• 80% code coverage?

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Mayflower GmbH 2009

Your projects...

• What‘s your average project lifetime?• Is there PHP code more than 5 years old?• How many lines of code?• How many change requests per year?• Has there been a specification?• Were all features in the first

release as specified?

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What is Refactoring?

„Refactoring is a disciplined technique for restructuring an existing body of code, altering its internal structure without changing its external behavior.“

-Martin Fowler, www.refactoring.com

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Why especially PHP?

Code Aging!6

(c) www.medrehab.com

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A PHP Project in 2000 ...

• no coding standards, no PHPDoc• no MVC, no Design Patterns• if you were lucky, someone used a

template system• nobody cared about XSS or CSRF

a lot of changes in business logics• never got refactored,

documentated or even tested ...

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... because it worked!

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In the year 2009

• change requests get more and more expensive

• the bug rate is always increasing

• the development team motivation is decreasing

• requirement changes are almost impossible

• new team members need a lot of time to be productive

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Management point of view

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rising frequency

Dead end!

Benefit per Change Request

Costs per Change Request

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Start refactoring now!11

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But hey, stop!

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Don‘t refactor ...

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• weeks before a important release

• only with a lot of junior developers

• parallel with development tasks

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Before starting refactoring

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• define a coding standard• avoids spaghetti code• speeds up maintainability• improves productivity

• fix your API specs• complete your documentation

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During the refactoring...

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• stay calm• take a lot of good developers and

a bunch of juniors• write tests, tests, tests• don‘t let developer refactor their

own code• don‘t let junior developers

refactor alone

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About Unittests

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• Testing is essential during refactoring• Problems

• most of old code isn‘t „unittestable“

• API breaks during refacotoring• Solution

• Selenium tests instead• iterative refactoring

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Okay, let‘s start!17

(c) BMW AG

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Back to Martin Fowler

„Refactoring is a disciplined technique for restructuring an existing body of code, altering its internal structure without changing its external behavior.“

-Martin Fowler, www.refactoring.com

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Forms of refactoring

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•Renaming

•Extraction

•Changing signature

•Pull up / Pull down

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Renaming

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/** * Remove a word from the stop word dictionary * * @param integer $id * * @return void */ public function remove($id) { $sql = sprintf("DELETE FROM $this->tablename WHERE id = %d AND lang = '%s'", $id, $this->language); $this->db->query($sql); }

Mayflower GmbH 2009

Renaming

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/** * Remove a word from the stop word dictionary * * @param integer $stopword_id ID of the stop word * * @return void */ public function remove($stopword_id) { $delete = sprintf("DELETE FROM $this->tablename WHERE id = %d AND lang = '%s'", $stopword_id, $this->language); $this->db->query($delete); }

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Restructuring

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/** * Remove a word from the stop word dictionary * * @param integer $stopword_id ID of the stop word * * @return void */ public function remove($stopword_id) { $delete = sprintf("DELETE FROM $this->tablename WHERE id = %d AND lang = '%s'", $stopword_id, $this->language); $this->db->query($delete); }

Mayflower GmbH 2009

Restructuring

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/** * Remove a word from the stop word dictionary * * @param integer $stopword_id ID of the stop word * * @return void */ public function remove($stopword_id) { $delete = sprintf("DELETE FROM %s WHERE id = %d AND lang = '%s'", $this->tablename, $stopword_id, $this->language); $this->db->query($delete); }

Mayflower GmbH 2009

Extraction

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/** * Remove a word from the stop word dictionary * * @param integer $stopword_id ID of the stop word * * @return void */ public function remove($stopword_id) { $delete = sprintf("DELETE FROM %s WHERE id = %d AND lang = '%s'", $this->tablename, $stopword_id, $this->language); $this->db->query($delete); }

Mayflower GmbH 2009

Extraction

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public function remove($stopword_id) { $delete = sprintf("DELETE FROM %s WHERE id = %d AND lang = '%s'", $this->tablename, $stopword_id, $this->language); $this->_execute($delete); }

private function _execute($query) { return $this->db->query($query) }

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Changing signature

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/** * Remove a word from the stop word dictionary * * @param integer $id ID of the stop word * * @return void */ public function remove($stopword_id) { $delete = sprintf("DELETE FROM %s WHERE id = %d AND lang = '%s'", $this->tablename, $stopword_id, $this->language); $this->db->query($delete); }

Mayflower GmbH 2009

Changing signature

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/** * Remove a word from the stop word dictionary * * @param integer $stopword_id ID of the stop word * @param boolean $logging Log removal? Default: false * * @return void */ public function remove($stopword_id, $logging = false) { $delete = sprintf("DELETE FROM %s WHERE id = %d AND lang = '%s'", $this->tablename, $stopword_id, $this->language); if ($logging) { $this->_logAction('removal', $stopword_id); } $this->db->query($delete); }

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Pull up / Pull down

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x

Mayflower GmbH 2009

Pull up / Pull down

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x

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Pull up / Pull down

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xx

x

Mayflower GmbH 2009

Tips & Tricks

• Always add PHPDoc if it‘s missing• Never trust automatic refactoring of IDEs• Don‘t do refactoring for fun• Write as much unittests as possible

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Any questions?

Mayflower GmbH 2009

Thank you very much for your attention!

Thorsten RinneMayflower GmbHMannhardtstraße 6D-80538 München+49 (0) 89 24 20 54 - 31thorsten.rinne@mayflower.de

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