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12. Template Method
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PHP Patterns
12. Template Method
pic.md Raw #
method1.php Raw #
<?php
abstract class Movie {
protected $name;
protected $budget;
protected $cast = [];
protected $director;
public function __construct (string $name) {
$this->name = $name;
}
public final function publish () {
$this->raiseMoney();
$this->castActors();
$this->castDirector();
$this->promote();
}
abstract protected function raiseMoney ();
abstract protected function castActors ();
abstract protected function castDirector ();
protected function promote () {
$actors = implode(", ", $this->cast);
echo "New movie '{$this->name}' directed by {$this->director}. Starring {$actors} and budget of \${$this->budget}!" . PHP_EOL;
}
}
class ComedyMovie extends Movie {
const AVAILABLE_DIRECTORS = ['Edgar Wright', 'Kevin Smith'];
const AVAILABLE_ACTORS = ['Jim Carrey', 'Eddie Murphy', 'Steve Carell'];
const NUM_ROLES = 2;
protected function raiseMoney () {
$this->budget = 500000;
}
protected function castActors () {
$this->cast[] = 'Adam Sandler';
$this->cast[] = self::AVAILABLE_ACTORS[array_rand(self::AVAILABLE_ACTORS)];
}
protected function castDirector () {
$this->director = self::AVAILABLE_DIRECTORS[array_rand(self::AVAILABLE_DIRECTORS)];
}
}
class ActionMovie extends Movie {
const AVAILABLE_DIRECTORS = ['Michael Bay', 'James Cameron', 'Steven Spielberg'];
const AVAILABLE_ACTORS = ['Sylvester Stallone', 'Bruce Willis', 'Al Pacino', 'Arnold Schwarzenegger'];
const NUM_ROLES = 2;
protected function raiseMoney () {
$this->budget = 100000;
}
protected function castActors () {
foreach (array_rand(self::AVAILABLE_ACTORS, self::NUM_ROLES) as $actor) {
$this->cast[] = self::AVAILABLE_ACTORS[$actor];
}
}
protected function castDirector () {
$this->director = self::AVAILABLE_DIRECTORS[array_rand(self::AVAILABLE_DIRECTORS)];
}
}
// USAGE
$actionMovie = new ActionMovie("Great action");
$actionMovie->publish();
$comedyMovie = new ComedyMovie("Comedy 2");
$comedyMovie->publish();method2.php Raw #
<?php
abstract class Journey
{
/**
* @var string[]
*/
private array $thingsToDo = [];
/**
* This is the public service provided by this class and its subclasses.
* Notice it is final to "freeze" the global behavior of algorithm.
* If you want to override this contract, make an interface with only takeATrip()
* and subclass it.
*/
final public function takeATrip()
{
$this->thingsToDo[] = $this->buyAFlight();
$this->thingsToDo[] = $this->takePlane();
$this->thingsToDo[] = $this->enjoyVacation();
$buyGift = $this->buyGift();
if ($buyGift !== null) {
$this->thingsToDo[] = $buyGift;
}
$this->thingsToDo[] = $this->takePlane();
}
/**
* This method must be implemented, this is the key-feature of this pattern.
*/
abstract protected function enjoyVacation(): string;
/**
* This method is also part of the algorithm but it is optional.
* You can override it only if you need to
*/
protected function buyGift(): ?string
{
return null;
}
private function buyAFlight(): string
{
return 'Buy a flight ticket';
}
private function takePlane(): string
{
return 'Taking the plane';
}
/**
* @return string[]
*/
public function getThingsToDo(): array
{
return $this->thingsToDo;
}
}
class BeachJourney extends Journey
{
protected function enjoyVacation(): string
{
return "Swimming and sun-bathing";
}
}
class CityJourney extends Journey
{
protected function enjoyVacation(): string
{
return "Eat, drink, take photos and sleep";
}
protected function buyGift(): ?string
{
return "Buy a gift";
}
}method3.php Raw #
<?php
namespace RefactoringGuru\TemplateMethod\RealWorld;
/**
* The Abstract Class defines the template method and declares all its steps.
*/
abstract class SocialNetwork
{
protected $username;
protected $password;
public function __construct(string $username, string $password)
{
$this->username = $username;
$this->password = $password;
}
/**
* The actual template method calls abstract steps in a specific order. A
* subclass may implement all of the steps, allowing this method to actually
* post something to a social network.
*/
public function post(string $message): bool
{
// Authenticate before posting. Every network uses a different
// authentication method.
if ($this->logIn($this->username, $this->password)) {
// Send the post data. All networks have different APIs.
$result = $this->sendData($message);
// ...
$this->logOut();
return $result;
}
return false;
}
/**
* The steps are declared abstract to force the subclasses to implement them
* all.
*/
abstract public function logIn(string $userName, string $password): bool;
abstract public function sendData(string $message): bool;
abstract public function logOut(): void;
}
/**
* This Concrete Class implements the Facebook API (all right, it pretends to).
*/
class Facebook extends SocialNetwork
{
public function logIn(string $userName, string $password): bool
{
echo "\nChecking user's credentials...\n";
echo "Name: " . $this->username . "\n";
echo "Password: " . str_repeat("*", strlen($this->password)) . "\n";
simulateNetworkLatency();
echo "\n\nFacebook: '" . $this->username . "' has logged in successfully.\n";
return true;
}
public function sendData(string $message): bool
{
echo "Facebook: '" . $this->username . "' has posted '" . $message . "'.\n";
return true;
}
public function logOut(): void
{
echo "Facebook: '" . $this->username . "' has been logged out.\n";
}
}
/**
* This Concrete Class implements the Twitter API.
*/
class Twitter extends SocialNetwork
{
public function logIn(string $userName, string $password): bool
{
echo "\nChecking user's credentials...\n";
echo "Name: " . $this->username . "\n";
echo "Password: " . str_repeat("*", strlen($this->password)) . "\n";
simulateNetworkLatency();
echo "\n\nTwitter: '" . $this->username . "' has logged in successfully.\n";
return true;
}
public function sendData(string $message): bool
{
echo "Twitter: '" . $this->username . "' has posted '" . $message . "'.\n";
return true;
}
public function logOut(): void
{
echo "Twitter: '" . $this->username . "' has been logged out.\n";
}
}
/**
* A little helper function that makes waiting times feel real.
*/
function simulateNetworkLatency()
{
$i = 0;
while ($i < 5) {
echo ".";
sleep(1);
$i++;
}
}
/**
* The client code.
*/
echo "Username: \n";
$username = readline();
echo "Password: \n";
$password = readline();
echo "Message: \n";
$message = readline();
echo "\nChoose the social network to post the message:\n" .
"1 - Facebook\n" .
"2 - Twitter\n";
$choice = readline();
// USAGE
// Now, let's create a proper social network object and send the message.
if ($choice == 1) {
$network = new Facebook($username, $password);
} elseif ($choice == 2) {
$network = new Twitter($username, $password);
} else {
die("Sorry, I'm not sure what you mean by that.\n");
}
$network->post($message);
// OUTPUT
/*
Username:
> neo
Password:
> 123123
Message:
> What is the Matrix?
Choose the social network to post the message:
1 - Facebook
2 - Twitter
> 1
Checking user's credentials...
Name: neo
Password: ******
.....
Facebook: 'neo' has logged in successfully.
Facebook: 'neo' has posted 'What is the Matrix?'.
Facebook: 'neo' has been logged out.
*/