Bringing your application into 2014

by Michael Heap

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Refactoring your application in 2014

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Refactoring your application

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A practical guide to surviving legacy code

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A practical guide to surviving any code

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I’m Michael! • @mheap on Twitter • Fifth time at PHPNW! • Developer at…

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No content

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Let me paint you a picture

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Job interview

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Job offer

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10am Start

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Awesome workstation

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$dbhost = 'localhost:3036';! $dbuser = 'root';! $dbpass = 'rootpassword';! $conn = mysql_connect($dbhost, $dbuser, $dbpass);! if(! $conn )! {! die('Could not connect: ' . mysql_error());! }! $sql = 'SELECT id, name FROM employee';! ! mysql_select_db('test_db');! $retval = mysql_query( $sql, $conn );! if(! $retval )! {! die('Could not get data: ' . mysql_error());! }! while($row = mysql_fetch_array($retval, MYSQL_ASSOC))! {! echo "EMP ID :{$row['id']}
".! "EMP NAME : {$row['name']}
".! "--------------------------------
";! } ! echo "Fetched data successfully\n";! mysql_close($conn);!

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The harsh truth

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All code is legacy code

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Not about intentions

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Fixing it

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Disclaimer

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Why put the effort in?

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Reduce complexity

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Increase maintainability

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Improve performance

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Better stability

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Prerequisites

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Refactor != Rewrite

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No new functionality

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Modern PHP

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Version control

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Choose a standard

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Leave the code a little better than you found it

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PSR

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PSR0/4

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PSR2

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Request lifecycle

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Dependency

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Action

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Response

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What about our code?

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".! "EMP NAME : {$row['name']}
".! "--------------------------------
";! } ! echo "Fetched data successfully\n";! mysql_close($conn);! ?>!

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Write a test

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Run the test

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".! "EMP NAME : {$row['name']}
".! "--------------------------------
";! } ! echo "Fetched data successfully\n";! mysql_close($conn);! ?>!

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".! "EMP NAME : {$row['name']}
".! "--------------------------------
";! } ! echo "Fetched data successfully\n";! mysql_close($conn);! ?>!

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…! ! mysql_select_db('test_db');! $retval = mysql_query( $sql, $conn );! if(! $retval )! {! die('Could not get data: ' . mysql_error());! }! while($row = mysql_fetch_array($retval, MYSQL_ASSOC))! {! echo "EMP ID :{$row['id']}
".! "EMP NAME : {$row['name']}
".! "--------------------------------
";! } ! ! …!

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…! ! mysql_select_db('test_db');! $retval = mysql_query( $sql, $conn );! if(! $retval )! {! die('Could not get data: ' . mysql_error());! }! ! $data = array();! ! while($row = mysql_fetch_array($retval, MYSQL_ASSOC))! {! ! $data[] = $row;! }! ! foreach ($data as $row)! echo "EMP ID :{$row['id']}
".! "EMP NAME : {$row['name']}
".! "--------------------------------
";! } ! ! …

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…! ! $data = array(! ! array("id" => 1, "name" => "Michael ")! );! ! foreach ($data as $row)! echo "EMP ID :{$row['id']}
".! "EMP NAME : {$row['name']}
".! "--------------------------------
";! } ! ! …!

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1, "name" => "Michael ")! );! ! include 'employee_view.php';! ! ?>!

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conn );! ! ! if(! $retval )! ! ! {! ! ! die('Could not get data: ' . mysql_error());! ! ! }! ! ! ! while($row = mysql_fetch_array($retval, MYSQL_ASSOC))! ! ! {! ! ! ! $data[] = $row;! ! ! }! ! ! ! return $data;! ! ! }! }!

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query('SELECT id, name FROM employee');! include 'employee_view.php';! ! include 'db_teardown.php';! ?>!

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query('SELECT id, name FROM employee');! ! }! }!

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db = $db;! ! }! ! ! public function getAllEmployees() {! ! ! return $this->db->query('SELECT id, name FROM employee');! ! }! }!

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getAllEmployees();! include 'employee_view.php';! ! include 'db_teardown.php';! ?>!

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class Db

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/src/Db.php

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class Foo_Bar_Baz

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/src/Foo/Bar/Baz.php

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class \mheap\Foo

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src mheap/Foo.php

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getAllEmployees();! include 'employee_view.php';! ?>!

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db = $db;! ! }! ! ! public function getAllEmployees() {! ! ! return $this->db->query('SELECT id, name FROM employee');! ! }! }!

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db = $db;! ! }! ! ! public function getAllEmployees() {! ! ! return $this->db->query(‘SELECT id, name FROM employee');! ! }! }!

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getAllEmployees();! include 'employee_view.php';! ?>!

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getAllEmployees();! ! $response = new Response();! ob_start();! include 'employee_view.php';! $reponse->content = ob_get_contents();! ob_end_clean();! ! $response->send();! ?>!

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assertEquals($response->content, "EMP ID: ...etc");! ! ?>!

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And more!

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Do it alongside your app

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Review

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Dependency

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Action

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Response

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Small, reusable classes

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Don’t change behaviour

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Useful tools

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PHPCS

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PHPMD

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PHPCPD

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“Don’t Repeat Yourself” was never about code. It’s about knowledge. It’s about cohesion. If two pieces of code represent the exact same knowledge, they will always change together. Having to change them both is risky: you might forget one of them. On the other hand, if two identical pieces of code represent different knowledge, they will change independently. De-duplicating them introduces risk, because changing the knowledge for one object, might accidentally change it for the other object. - http://verraes.net/2014/08/dry-is-about-knowledge/

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Qafoo Refactoring Tools

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Scrutinizer CI

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The parts that didn’t fit

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Testing legacy code

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Working with external dependencies

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Most of the PHP-FIG work

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Logging strategies

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Automation

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Effective version control

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Find me later

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Parting thoughts

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Perfect is the enemy of better

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Optimise for reading code

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$ordersWithProducts rather than $data.

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markReadAndNotifyUser() rather than markRead(true)

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Constants are good

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Code doesn't lie

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Any questions?

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Thank you http://joind.in/11802