implements Hello_Dolly

implements Hello_Dolly
Image Credit: Ky on Flickr • https://flic.kr/p/8x4bVQ
Jonathan Brinley • • #wcorl • Slides: @jbrinley flightless.us/wcorl2016

Jonathan Brinley

"Hello, Dolly!"
Image Credit: Classic Film on Flickr • https://flic.kr/p/KD7WWE

"Hello, Dolly!"

hello.php
/**
* @package Hello_Dolly
* @version 1.6
*/
/*
Plugin Name: Hello Dolly
Plugin URI: http://wordpress.org/plugins/hello-dolly/
Description: This is not just a plugin, it symbolizes the hope and enthusiasm of an entire generation summed up in
Author: Matt Mullenweg
Version: 1.6
Author URI: http://ma.tt/
*/
function hello_dolly_get_lyric() {
/** These are the lyrics to Hello Dolly */
$lyrics = "Hello, Dolly
Well, hello, Dolly
It's so nice to have you back where you belong
You're lookin' swell, Dolly
I can tell, Dolly
You're still glowin', you're still crowin'
You're still goin' strong
We feel the room swayin'

Refactor!
github.com/flightless/implements-hello-dolly
Image Credit: Classic Film on Flickr • https://flic.kr/p/LxazKW

implements-hello-dolly.php
/*
Plugin Name: implements Hello_Dolly
Description: We start with everyone’s favorite WordPress plugin, “Hello, Dolly”. With a dramatic wave of our hands, w
Author: Jonathan Brinley
Version: 2.0
Contributors: Matt Mullenweg
*/
namespace Hello_Dolly;
// Start the plugin
add_action( 'plugins_loaded', function () {
require_once __DIR__ . '/vendor/autoload.php';
Hello_Dolly_Plugin::init();
do_action( 'hello_dolly/init' );
}, 1, 0 );

Composer
Autoloading
Libraries
getcomposer.org

Composer
composer init
{
"name": "flightless/implements-hello-dolly",
"description": "We start with everyone’s favorite WordPress plugin, “Hello, Dolly”. With a dramatic wave of our ha
"type": "wordpress-plugin",
"license": "GPL-2.0",
"authors": [
{
"name": "Jonathan Brinley",
"email": "jonathan@tri.be"
}
]
}

composer.json
{
"description": "We start with everyone’s favorite WordPress plugin, “Hello, Dolly”. With a dramatic wave of our ha
"type": "wordpress-plugin",
"license": "GPL-2.0",
"authors": [
{
"name": "Jonathan Brinley",
"email": "jonathan@tri.be"
}
],
"autoload": {
"psr-4": {
"Hello_Dolly": "src/"
}
}
}

Codeception
composer require --dev lucatume/wp-browser

Codeception
composer install --no-dev
{
/* ... */
"autoload": {
"psr-4": {
"Hello_Dolly": "src/"
}
},
"require-dev": {
"lucatume/wp-browser": "^1.16"
}
}

WPLoader
vendor/bin/wpcept bootstrap
https://github.com/lucatume/wp-browser

tests/integration/Hello_Dolly/ Hello_Dolly_Plugin_Test.php
use CodeceptionTestCaseWPTestCase;
class Hello_Dolly_Plugin_Test extends WPTestCase {
public function test_get_instance() {
$instance = Hello_Dolly_Plugin::instance();
$this->assertInstanceOf( 'Hello_DollyHello_Dolly_Plugin', $instance );
}
}

// Start the plugin
Hello_Dolly_Plugin::init();
do_action( 'hello_dolly/init' );
}, 1, 0 );

src/Hello_Dolly_Plugin.php
/**
* Initializes the Hello, Dolly plugin
*/
class Hello_Dolly_Plugin {
/** @var static */
private static $instance;
/**
* Initialize the plugin
*/
public static function init() {
self::instance();
}
/**
* Get the global instance of the class
* @return static
*/
public static function instance() {
if ( empty( static::$instance ) ) {
static::$instance = new static();
}

First Five Principles
Single responsibility principle
Open/closed principle
Liskov substitution principle
Interface segregation principle
Dependency inversion principle

Single responsibility principle
Turn a string of lyrics into an array
Get a random line from the lyrics array
Texturize a line of lyrics
Wrap lyrics in a paragraph tag
Build language-appropriate CSS rules
Print the lyrics to the browser
Print the style rules to the browser
Hook into WordPress

LyricsLyric_Collection
Responsibility
Fetch a single line from an array of lyrics
Why would it change?
If the algorithm to fetch a line changed

tests/integration/Hello_Dolly/ Lyrics/Lyric_Collection_Test.php
namespace Hello_DollyLyrics;
class Lyric_Collection_Test extends WPTestCase {
public function test_get_lyric() {
$lyrics = [];
for ( $i = 0 ; $i < 10 ; $i++ ) {
$lyrics[] = rand_str( mt_rand( 0, 32 ) ) . ' ' . rand_str( mt_rand( 0, 32 ) ) . ' ' . rand_str( mt_rand( 0, 32
}
$collection = new Lyric_Collection( $lyrics );
for ( $i = 0 ; $i < 20 ; $i++ ) {
$this->assertContains( $collection->get_lyric(), $lyrics );
}
}
}

LyricsLyric_Collection
class Lyric_Collection implements Lyric_Collection_Interface {
/** @var string[] */
protected $lyrics;
/** @var int */
protected $count = 0;
/**
* Lyric_Collection constructor.
*
* @param array $lyrics An array of single-line strings
*/
public function __construct( array $lyrics ) {
$this->lyrics = array_values( $lyrics );
$this->count = count( $this->lyrics );
}
public function get_lyric() {
return $this->get_random_lyric();
}
/**

LyricsLyric_Collection_Interface
/**
* Interface Lyric_Collection_Interface
*
* Implementors will return a single line of lyrics
*/
interface Lyric_Collection_Interface {
/**
* @return string A single line of lyrics
*/
public function get_lyric();
}

LyricsLyric_Collection_Factory
Responsibility
Transform a string of lyrics into a Lyric_Collection
If the return value should be a different class

tests/integration/Hello_Dolly/
Lyrics/Lyric_Collection_Factory_Test.php
class Lyric_Collection_Factory_Test extends WPTestCase {
public function test_create_collection() {
$lyrics = [];
for ( $i = 0 ; $i < 10 ; $i++ ) {
$lyrics[] = rand_str( mt_rand( 0, 32 ) ) . ' ' . rand_str( mt_rand( 0, 32 ) ) . ' ' . rand_str( mt_rand( 0, 32
}
$string = implode( "n", $lyrics );
$factory = new Lyric_Collection_Factory();
$collection = $factory->create_collection( $string );
$this->assertInstanceOf( 'Hello_DollyLyricsLyric_Collection', $collection );
}
}

LyricsLyric_Collection_Factory
/**
* Class Lyric_Collection_Factory
*
* Creates a Lyric_Collection instance from
* a string of lyrics.
*/
class Lyric_Collection_Factory implements Lyric_Collection_Factory_Interface {
/**
* @param string $lyrics
* @return Lyric_Collection
*/
public function create_collection( $lyrics ) {
$lyrics = explode( "n", $lyrics );
return new Lyric_Collection( $lyrics );
}
}

LyricsLyric_Collection_Factory_Interface
/**
* Interface Lyric_Collection_Factory_Interface
*
* Creates a Lyric_Collection_Interface from a
* multi-line string of lyrics.
*/
interface Lyric_Collection_Factory_Interface {
/**
* @param string $lyrics A multi-line string of lyrics
* @return Lyric_Collection_Interface
*/
public function create_collection( $lyrics );
}

Formatting
Responsibility
Apply wptexturize() to a string
Wrap a string in a paragraph tag with an ID
The formatting algorithm changes
The HTML element changes

Decorator
format(string)
String_Formatter
format(string)
String_Formatter
format(string)
String_Formatter_Interface
format(string)
String_Formatter_Interface
html_id
__construct(formatter, html_id)
decorate(string)
Paragraph_Tag
html_id
__construct(formatter, html_id)
decorate(string)
Paragraph_Tag
decorate(string)
WP_Texturize_Formatter
decorate(string)
WP_Texturize_Formatter
formatter
__construct(formatter)
format(string)
decorate(string)
String_Formatter_Decorator
formatter
__construct(formatter)
format(string)
decorate(string)
String_Formatter_Decorator

FormattingString_Formatter_Interface
namespace Hello_DollyFormatting;
/**
* Interface String_Formatter_Interface
*
* Implementors will format and return a string.
*/
interface String_Formatter_Interface {
/**
* @param string $string The string to be formatted
* @return string The formatted string
*/
public function format( $string );
}

FormattingString_Formatter
class String_Formatter_Test extends WPTestCase {
public function test_passthrough() {
$string = rand_str();
$passthrough = new String_Formatter();
$this->assertEquals( $string, $passthrough->format( $string ) );
}
}

FormattingString_Formatter
/**
* Class String_Formatter
*
* A passthrough formatter that returns the given string
*/
class String_Formatter implements String_Formatter_Interface {
public function format( $string ) {
return $string;
}
}

FormattingString_Formatter_Decorator
/**
* Class String_Formatter_Decorator
*
* Base class for string decorators.
*/
abstract class String_Formatter_Decorator implements String_Formatter_Interface {
/** @var String_Formatter_Interface */
protected $formatter;
public function __construct( String_Formatter_Interface $formatter ) {
$this->formatter = $formatter;
}
public function format( $string ) {
$string = $this->formatter->format( $string );
return $this->decorate( $string );
}
abstract protected function decorate( $string );
}

FormattingWP_Texturize_Formatter
class WP_Texturize_Formatter_Test extends WPTestCase {
public function test_texturization() {
$string = "You're lookin' swell, Dolly";
$texturized_string = wptexturize( $string );
$this->assertNotEquals( $string, $texturized_string );
$formatter = new WP_Texturize_Formatter( new String_Formatter() );
$this->assertEquals( $texturized_string, $formatter->format( $string ) );
}
}

FormattingWP_Texturize_Formatter
/**
* Class WP_Texturize_Formatter
*
* Formats a string with wptexturize()
* @see wptexturize()
*/
class WP_Texturize_Formatter extends String_Formatter_Decorator {
protected function decorate( $string ) {
return wptexturize( $string );
}
}

FormattingParagraph_Tag
class Paragraph_Tag_Test extends WPTestCase {
public function test_paragraph_tag() {
$id = rand_str();
$formatter = new Paragraph_Tag( new String_Formatter(), $id );
$expected = sprintf( '%s', $id, $string );
$this->assertEquals( $expected, $formatter->format( $string ) );
}
public function test_escaped_id() {
$id = rand_str(8) . ' ' . rand_str(8);
$escaped_id = sanitize_html_class( $id );
$this->assertNotEquals( $id, $escaped_id );
$formatter = new Paragraph_Tag( new String_Formatter(), $id );
$expected = sprintf( '%s', $escaped_id, $string );
$this->assertEquals( $expected, $formatter->format( $string ) );

FormattingParagraph_Tag
/**
* Class Paragraph_Tag
*
* Wraps a string in a paragraph tag with an ID
*/
class Paragraph_Tag extends String_Formatter_Decorator {
/** @var string */
protected $html_id;
/**
* Paragraph_Tag constructor.
*
* @param String_Formatter_Interface $formatter
* @param $html_id
*/
public function __construct( String_Formatter_Interface $formatter, $html_id ) {
parent::__construct( $formatter );
$this->html_id = $html_id;
}
protected function decorate( $string ) {
return sprintf( '%s', sanitize_html_class( $this->html_id), $string );

You’re lookin’ swell, Dolly
$formatter = new Paragraph_Tag(
new WP_Texturize_Formatter(
new String_Formatter()
),
'dolly'
);
return $formatter->format( "You're lookin' swell, Dolly" );

StylesStyle_Rules_Interface
namespace Hello_DollyStyles;
/**
* Interface Style_Rules_Interface
*
* Generates a list of CSS properties
*/
interface Style_Rules_Interface {
/**
* @return string
*/
public function get_styles();
}

StylesDirectional_Style_Rules
/**
* Class Directional_Style_Rules
*
* Generates styles for the given text direction
*/
class Directional_Style_Rules implements Style_Rules_Interface {
protected $side;
/**
* Directional_Style_Rules constructor.
*
* @param string $side The side text floats to. 'left' or 'right'
*/
public function __construct( $side ) {
if ( empty( $side ) ) {
throw new InvalidArgumentException( __( '$this->side must be set to a non-empty value' ) );
}
$this->side = $side;
}
public function get_styles() {
return "

StylesStyle_Printer_Interface
/**
* Interface Style_Printer_Interface
*
* Prints CSS styles
*/
interface Style_Printer_Interface {
/**
* @param Style_Rules_Interface $styles
* @return void
*/
public function print_styles( Style_Rules_Interface $styles );
}

StylesStyle_Printer
/**
* Class Style_Printer
*
* Prints the given style rules for the element with the given ID
*/
class Style_Printer implements Style_Printer_Interface {
protected $html_id;
/**
* Style_Printer constructor.
*
* @param string $html_id The ID of the targeted DOM element
*/
public function __construct( $html_id ) {
$this->html_id = $html_id;
}
/**
* @param Style_Rules_Interface $styles
* @return void
*/
public function print_styles( Style_Rules_Interface $styles ) {

private function hooks() {
add_action( 'admin_head', [ $this, 'print_admin_css' ] );
add_action( 'admin_notices', [ $this, 'print_admin_notice' ] );
}
public function print_admin_css() {
$style_rules = $this->get_style_rules();
$printer = $this->get_style_printer();
$printer->print_styles( $style_rules );
}
public function print_admin_notice() {
$lyrics = $this->get_lyric_collection();
$printer = $this->get_lyric_printer();
$printer->render( $lyrics->get_lyric() );
}

/**
* @return Style_Rules_Interface
*/
private function get_style_rules() {
if ( is_rtl() ) {
$style_rules = $this->container[ 'style_rules.rtl' ];
} else {
$style_rules = $this->container[ 'style_rules.ltr' ];
}
return apply_filters( 'hello_dolly/style_rules', $style_rules );
}
/**
* @return Style_Printer_Interface
*/
private function get_style_printer() {
$printer = $this->container[ 'style_printer' ];
return apply_filters( 'hello_dolly/style_printer', $printer );
}
/**
* @return Lyric_Collection_Interface
*/
private function get_lyric_collection() {

/**
* Initialize the plugin
*
* @return void
*/
public static function init( Container $container ) {
$instance = self::instance();
$instance->container = $container;
$instance->hooks();
}

Dependency Injection Container
Aura.Di
PHP-DI
Pimple
SymphonyDependencyInjection
ZendDi

Pimple
composer require pimple/pimple

use PimpleContainer;
// Start the plugin
$container = new Container();
$container->register( new Service_Provider() );
Hello_Dolly_Plugin::init( $container );
do_action( 'hello_dolly/init', Hello_Dolly_Plugin::instance(), $container );
}, 1, 0 );

src/Service_Provider.php
use Hello_DollyFormattingParagraph_Tag;
use Hello_DollyFormattingString_Formatter;
use Hello_DollyFormattingWP_Texturize_Formatter;
use Hello_DollyLyricsLyric_Collection_Factory;
use Hello_DollyPrintingFormatted_Printer;
use Hello_DollyStylesDirectional_Style_Rules;
use Hello_DollyStylesStyle_Printer;
use PimpleContainer;
use PimpleServiceProviderInterface;
class Service_Provider implements ServiceProviderInterface {
public function register( Container $container ) {
$container[ 'html_id' ] = 'dolly';
$container[ 'lyrics' ] = "Hello, Dolly
Well, hello, Dolly
It's so nice to have you back where you belong
You're lookin' swell, Dolly
I can tell, Dolly
You're still glowin', you're still crowin'

Resources
implements Hello_Dolly
github.com/flightless/implements-hello-dolly
The Principles of OOD / Robert C. Martin
butunclebob.com/ArticleS.UncleBob.PrinciplesOfOod
Inversion of Control Containers and the Dependency Injection pattern / Martin Fowler
martinfowler.com/articles/injection.html
WPBrowser / Luca Tumedei
github.com/lucatume/wp-browser
theaveragedev.com/tag/wp-browser/
Image Credit: New York Sunday News

Jonathan Brinley
@jbrinley • jonathan@tri.be

implements Hello_Dolly

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