Php 接口注入和公共类

我正试图了解OOP原则，并编写自己的类。作为学习的一种方式，我决定将我在Wordpress中编写的两个函数转换为OOP类。这些函数协同工作，以便根据URL中设置的引用者（其中4个）在单个页面上输出正确的帖子链接

这是带有基本工作流程的设置（工作流程可以随操作而更改）：

根据归档页面为URL设置了4个查询变量，即一个用于分类页面的查询变量，一个用于作者页面的查询变量，等等。任何页面都不能有多个自定义查询变量。这4个变量由我的第一个类检索，并根据给定的全局变量进行检查，在本例中为

$\u GET

。我没有在我的类中硬编码这4个变量，这也有助于

$\u GET

保持类的可测试性。如果URL中存在该值，则通过

has*

方法返回键/值对。如果没有找到匹配项，这些方法将返回

null

。（这是原始数据，将由使用此数据的类进行清理/转义）

这是全班同学

<?php
namespace PG\Single\Post\Navigation;

/**
 * Test set values against the super global given. Returns conditional properties
 * which is boolean values. true is returned on success and false on failure.
 *
 * @param $superGlobalVar Super global to test the values against
 * @param (string) $authorReferrer 
 * @param (string) $dateReferrer 
 * @param (string) $searchReferrer 
 * @param (string) $taxReferrer 
*/ 
class RequestReferrerHandler implements RequestReferrerHandlerInterface
{
    /**
     * @since 1.0.0
     * @access protected
     * @var (array) $superGlobalVar
    */
    protected $superGlobalVar;

    /**
     * @since 1.0.0
     * @access protected
     * @var (string) $authorReferrer
    */
    protected $authorReferrer;

    /**
     * @since 1.0.0
     * @access protected
     * @var (string) $dateReferrer
    */
    protected $dateReferrer;

    /**
     * @since 1.0.0
     * @access protected
     * @var (string) $searchReferrer
    */
    protected $searchReferrer;

    /**
     * @since 1.0.0
     * @access protected
     * @var (string) $taxReferrer
    */
    protected $taxReferrer;


    /**
     * Public constructor method.
     *
     * @param $superGlobalVar  Super global to get data from
     * @param $authorReferrer  Query variable from author referrer to test
     * @param $dateReferrer    Query variable from date referrer to test
     * @param $searchReferrer  Query variable from search referrer to test
     * @param $taxReferrer     Query variable from taxonomy referrer to test
    */
    public function __construct($superGlobalVar = null, $authorReferrer= null, $dateReferrer = null, $searchReferrer = null, $taxReferrer = null)
    {
        $this->superGlobalVar = $superGlobalVar;
        $this->authorReferrer = $authorReferrer;
        $this->dateReferrer   = $dateReferrer;
        $this->searchReferrer = $searchReferrer;
        $this->taxReferrer    = $taxReferrer;
    }

    /**
     * Setter setSuperGlobalVar.
     *
     * @since 1.0.0
     * @param $superGlobalVar
     * @return $this
     */
    public function setSuperGlobalVar($superGlobalVar)
    {
        $this->superGlobalVar = $superGlobalVar;
        return $this;
    }   

    /**
     * Returns an array of super global variables.
     *
     * @since 1.0.0
     * @return (array) $this->superGlobalVar
    */ 
    public function getSuperGlobalVar()
    {
        return $this->superGlobalVar;
    }

    /**
     * Setter setAuthorReferrer
     *
     * @since 1.0.0
     * @param $authorReferrer
     * @return $this
     */
    public function setAuthorReferrer($authorReferrer)
    {
        $this->authorReferrer = $authorReferrer;
        return $this;
    }   

    /**
     * Returns the value of the $authorReferrer property.
     *
     * @since 1.0.0
     * @return (array) $this->authorReferrer
    */ 
    public function getAuthorReferrer()
    {
        return $this->authorReferrer;
    }

    /**
     * Setter setDateReferrer.
     *
     * @since 1.0.0
     * @param $dateReferrer
     * @return $this
     */
    public function setDateReferrer($dateReferrer)
    {
        $this->dateReferrer = $dateReferrer;
        return $this;
    }   

    /**
     * Returns the value of the $dateReferrer property.
     *
     * @since 1.0.0
     * @return (array) $this->dateReferrer
    */ 
    public function getDateReferrer()
    {
        return $this->dateReferrer;
    }

    /**
     * Setter setSearchReferrer.
     *
     * @since 1.0.0
     * @param $searchReferrer
     * @return $this
     */
    public function setSearchReferrer($searchReferrer)
    {
        $this->searchReferrer = $searchReferrer;
        return $this;
    }   

    /**
     * Returns the value of the $searchReferrer property.
     *
     * @since 1.0.0
     * @return (array) $this->searchReferrer
    */ 
    public function getSearchReferrer()
    {
        return $this->searchReferrer;
    }

    /**
     * Setter setTaxReferrer.
     *
     * @since 1.0.0
     * @param $taxReferrer
     * @return $this
     */
    public function setTaxReferrer($taxReferrer)
    {
        $this->taxReferrer = $taxReferrer;
        return $this;
    }   

    /**
     * Returns the value of the $taxReferrer property.
     *
     * @since 1.0.0
     * @return (array) $this->taxReferrer
    */ 
    public function getTaxReferrer()
    {
        return $this->$taxReferrer;
    }

    /**
     * Test $authorReferrer against $superGlobalVar.
     *
     * @since 1.0.0
     * @return (bool) true on success or false on failure
     */
    public function isAuthorReferrer()
    {
        if ($this->authorReferrer && isset($this->superGlobalVar[$this->authorReferrer])) { 
            $isAuthorReferrer = true;
        } else {
            $isAuthorReferrer = false;
        }
        return $isAuthorReferrer;
    }

    /**
     * Test $authorReferrer against $superGlobalVar
     *
     * @since 1.0.0
     * @return (bool) true on success or false on failure
     */
    public function isDateReferrer()
    {
        if ($this->dateReferrer && isset($this->superGlobalVar[$this->dateReferrer])) { 
            $isDateReferrer = true;
        } else {
            $isDateReferrer = false;
        }
        return $isDateReferrer;
    }

    /**
     * Test $authorReferrer against $superGlobalVar.
     *
     * @since 1.0.0
     * @return (bool) true on success or false on failure
     */
    public function isSearchReferrer()
    {
        if ($this->searchReferrer && isset($this->superGlobalVar[$this->searchReferrer])) { 
            $isSearchReferrer = true;
        } else {
            $isSearchReferrer = false;
        }
        return $isSearchReferrer;
    }

    /**
     * Test $authorReferrer against $superGlobalVar.
     *
     * @since 1.0.0
     * @return (bool) true on success or false on failure
     */
    public function isTaxReferrer()
    {
        if ($this->taxReferrer && isset($this->superGlobalVar[$this->taxReferrer])) { 
            $isTaxReferrer = true;
        } else {
            $isTaxReferrer = false;
        }
        return $isTaxReferrer;
    }

    /**
     * Conditional which check if the current post is a referred post.
     *
     * @since 1.0.0
     * @return (bool) true on success or false on failure
     */
    public function isReferredPost()
    {
        if ($this->isAuthorReferrer() || $this->isDateReferrer() || $this->isSearchReferrer() || $this->isTaxReferrer()) {
            $isReferredPost = true;
        } else {
            $isReferredPost = false;
        }
        return $isReferredPost;
    }

    /**
     * Return the value from the super global when the current post is a post referred from
     * an author archive page.
     *
     * @since 1.0.0
     * @return (array) $authorReferrerValue
     */ 
    public function hasAuthorReferrerValue()
    {
        if ($this->isAuthorReferrer()) {
            $authorReferrerValue = [$this->authorReferrer => $this->superGlobalVar[$this->authorReferrer]];
        } else {
            $authorReferrerValue = null;
        }
        return $authorReferrerValue;
    }

    /**
     * Return the value from the super global when the current post is a post referred from
     * a date archive page.
     *
     * @since 1.0.0
     * @return (array) $dateReferrerValue
     */ 
    public function hasDateReferrerValue()
    {
        if ($this->isDateReferrer()) {
            $dateReferrerValue = [$this->dateReferrer => $this->superGlobalVar[$this->dateReferrer]];
        } else {
            $dateReferrerValue = null;
        }
        return $dateReferrerValue;
    }

    /**
     * Return the value from the super global when the current post is a post referred from
     * a search page.
     *
     * @since 1.0.0
     * @return (array) $searchReferrerValue
     */ 
    public function hasSearchReferrerValue()
    {
        if ($this->isSearchReferrer()) {
            $searchReferrerValue = [$this->searchReferrer => $this->superGlobalVar[$this->searchReferrer]];
        } else {
            $searchReferrerValue = null;
        }
        return $searchReferrerValue;
    }

    /**
     * Return the value from the super global when the current post is a post referred from
     * a taxonomy archive page.
     *
     * @since 1.0.0
     * @return (array) $taxReferrerValue
     */ 
    public function hasTaxReferrerValue()
    {
        if ($this->isTaxReferrer()) {
            $taxReferrerValue = [$this->taxReferrer => $this->superGlobalVar[$this->taxReferrer]];
        } else {
            $taxReferrerValue = null;
        }
        return $taxReferrerValue;
    }

}

作为一个示例，下面是两个类的外观示例。（为了使代码更易于管理，我省略了这里的一些方法）

甲级

---

如果您想将
RequestReferrerHandler
类的同一对象用于ClassA和ClassB，那么您的策略是正确的。只需要使用
RequestReferrerHandler
类的对象来实例化ClassA和ClassB。然后您可以访问特定的方法。i、 e.
ClassA.queryArguments（）
或
ClassB.queryVars（）

如果要为ClassA和ClassB创建单独的
requestReferreHandler
类对象，可以将
requestReferreHandler
类扩展到ClassA和ClassB，而无需定义构造函数。因此，当您创建ClassA的对象时，它会自动继承
RequestReferrerHandler
类的构造函数方法，您可以通过
parent:
关键字访问属性和方法。例如：

abstract class AbstractSanitizer implements SanitizerInterface
{
    protected $handler;

    public function __construct() {}

    public function setHandler(RequestReferrerHandlerInterface $handler)
    {
        $this->handler = $handler;
    }   

    /* For this example we are saying that sanitizeDate(), sanitizeTaxonomy() and
     * sanitizeSearch() will be the same no matter what.  So let's implement them 
     * and leave the child classes to implement sanitizeAuthor(). 
     * 
     * Implement the details of the sanitizer function to fit your needs.
     */

    public function sanitizeDate()
    {
        if($this->handler !== null)
        {
            //Perform whatever tasks to sanitize the date
            $sanitized = strtoupper($this->handler->getDateReferrer());
            echo "Sanitize date -> switch to uppercase letters.\n";
            $this->handler->setDateReferrer($sanitized);
        }
    }

    public function sanitizeSearch()
    {
        if($this->handler !== null)
        {
            //Perform whatever tasks to sanitize the search
            $sanitized = strtolower($this->handler->getSearchReferrer());
            echo "Sanitize search -> switch to lowercase letters.\n";
            $this->handler->setSearchReferrer($sanitized);
        }
    }

    public function sanitizeTaxonomy()
    {
        if($this->handler !== null)
        {
            //Perform whatever tasks to sanitize the taxonomy
            $sanitized = str_replace(" ", "_", $this->handler->getTaxReferrer());
            echo "Sanitize Taxonomy -> convert spaces to underscores.\n";
            $this->handler->setTaxReferrer($sanitized);
        }
    }

}

// Standard OOP
$car = new Car();
$buyer = new Person();
$store = new Store();

// Many solutions to buy a car!
$buyer->buy($car, $store);
// or
$store->sell($car, $buyer);
// or
// ...

你可以做和B类一样的事情。现在，您可以为类a和类B创建对象，在类C中为它们的基类指定构造函数的参数，并使用它们的对象的返回值
ClassA.queryArguments（）
或
ClassB.queryVars（）
。
查看代码，您肯定有了一个良好的开始。在使用OOP编程时，您已经使用了一个很好的经验法则-编程到接口，而不是实现。接口这个术语不仅指实际接口，也指抽象类

// Composition
class Car implements VehicleInterface
{
    private $motor;
}

class Motor implements MotorInterface

因此，在问题的核心，您希望有两个类，
ClassA
和
ClassB
，它们都使用
requestrefererhandler
中的常用方法。您已经为您的接口
requestReferreHandlerInterface
做了准备工作。我们可以说，您有一个如下所示的界面：

interface RequestReferrerHandlerInterface
{
    public function hasAuthorReferrerValue();
    public function hasDateReferrerValue();
    public function hasSearchReferrerValue();
    public function hasTaxReferrerValue();
    public function getAuthorReferrer();
    public function getDateReferrer();
    public function getSearchReferrer();
    public function getTaxReferrer();
    public function setAuthorReferrer($author);
    public function setDateReferrer($date);
    public function setSearchReferrer($search);
    public function setTaxReferrer($tax);
}

只要此接口是由
requestrefererhandler
实现的，您就可以键入提示接口作为
ClassA
和
ClassB
的构造函数要求。但这并不是什么新鲜事，因为你已经在这么做了

有两件事在我看来特别突出，那就是潜在的拇指酸痛。首先，由于您希望类的责任很小，因此您应该负责将数据提供给
requestrefererhandler
，而不是提供给
控制器。换句话说，不要将
$\u GET
注入到您的类中。确保您的<代码>控制器<代码>拥有正确创建<代码> RequestReferrerHandler < /代码>所需的所有信息。让我们看一下您的<代码> RequestReferrerHandler <代码>类，用它需要的所有方法刷新。
class SanitizerForClassA extends AbstractSanitizer
{
    /* This class must provide an implementation for how ClassA will
     * handle the sanitizeAuthor() method.
     */

    public function sanitizeAuthor()
    {
        if($this->handler !== null)
        {
            //Perform whatever tasks to sanitize the for ClassA
            $sanitized = array("author" => $this->handler->getAuthorReferrer());
            echo "Sanitize author -> ClassA makes author an array.\n";
            $this->handler->setAuthorReferrer($sanitized);
        }   
    }
}

class SanitizerForClassB extends AbstractSanitizer
{
    /* This class must provide an implementation for how ClassB will
     * handle the sanitizeAuthor() method.
     */

    public function sanitizeAuthor()
    {
        if($this->handler !== null)
        {
            //Perform whatever tasks to sanitize the for ClassB
            $sanitized = new stdClass();
            $sanitized->author = $this->handler->getAuthorReferrer();
            echo "Sanitize author -> ClassB makes author an object property. \n";
            $this->handler->setAuthorReferrer($sanitized);
        }   
    }
}

第二件突出的事情是
santize（）
方法。您是否看到它们在
ClassA
和
ClassB
中是如何复制的？两个类中的
sanitizeAuthor（）
是不同的，但是其余的呢？在这种情况下，干燥（不要重复自己）原则可以提供帮助。由于多个类可能必须以类似的方式清理数据，因此将其从类中抽象出来是有意义的

让我们看看如何做到这一点，然后我们将回到您的具体课程。首先创建一个新接口，该接口将指定可以清理数据的对象必须公开的方法

interface SanitizableHandlerInterface
{       
    public function __construct(RequestReferrerHandlerInterface $handler, SanitizerInterface $sanitizer);
}

interface QueryVarsInterface extends SanitizableHandlerInterface
{
    public function queryVars();
}

interface QueryArgumentsInterface extends SanitizableHandlerInterface
{
    public function queryArguments();
}

现在，如果您拥有的
ClassX
的每个对象都以不同的方式实现了这四个方法，那么您可以开始在不同的类中实现它，这些类只是清理数据。然而，对于这个例子，我们会说情况并非如此。让我们假设
sanitizeAuthor（）
在
ClassA
和
ClassB
（在您的代码中）之间可能不同，并且所有其他方法的实现都完全相同。在这种情况下，我们可以使用一个抽象类来实现sanitizer方法

class ClassA implements QueryArgumentsInterface
{
    private $handler;
    private $sanitizer;

    public function __construct(RequestReferrerHandlerInterface $handler, SanitizerInterface $sanitizer)
    {
        $this->handler = $handler;
        $this->sanitizer = $sanitizer;
        $this->sanitizer->setHandler($this->handler);
    }

    public function queryArguments() // Will be used in the controller class ClassC
    {
        $queryArgs = null;
        if($this->handler->hasAuthorReferrerValue())
        {
            $this->sanitizer->sanitizeAuthor();
            $queryArgs = $this->handler->getAuthorReferrer();
        }
        if($this->handler->hasDateReferrerValue())
        {
            $this->sanitizer->sanitizeDate();
            $queryArgs = $this->handler->getDateReferrer();
        }
        if($this->handler->hasSearchReferrerValue())
        {
            $this->sanitizer->sanitizeSearch();
            $queryArgs = $this->handler->getSearchReferrer();
        }
        if($this->handler->hasTaxReferrerValue())
        {
            $this->sanitizer->sanitizeTaxonomy();
            $queryArgs = $this->handler->getTaxReferrer();
        }
        return $queryArgs; //Will return null if all 4 conditions fail or return the value from the one that returns true
    }

}

class ClassB implements QueryVarsInterface
{
    private $handler;
    private $sanitizer;

    public function __construct(RequestReferrerHandlerInterface $handler, SanitizerInterface $sanitizer)
    {
        $this->handler = $handler;
        $this->sanitizer = $sanitizer;
        $this->sanitizer->setHandler($this->handler);       
    }

    public function queryVars() // Will be used in the controller class ClassC
    {
        $queryVars = null;
        if($this->handler->hasAuthorReferrerValue())
        {
            $this->sanitizer->sanitizeAuthor();
            $queryVars = $this->handler->getAuthorReferrer();
        }
        if($this->handler->hasDateReferrerValue())
        {
            $this->sanitizer->sanitizeDate();
            $queryVars = $this->handler->getDateReferrer();
        }
        if($this->handler->hasSearchReferrerValue())
        {
            $this->sanitizer->sanitizeSearch();
            $queryVars = $this->handler->getSearchReferrer();
        }
        if($this->handler->hasTaxReferrerValue())
        {
            $this->sanitizer->sanitizeTaxonomy();
            $queryVars = $this->handler->getTaxReferrer();
        }
        return $queryVars; //Will return null if all 4 conditions fail or return the value from the one that returns true
    }
}

有些事情需要立即注意。首先，您会注意到有一个
setHandler（）
方法，它接受
requestReferreHandlerInterface
的实例。这是为什么？大多数情况下都很方便。由于我们已经采取了清理行为并将其封装到自己的类中，因此我们为清理器提供了一种方法来更新具体的
requestrefererhandler
，它正在使用清理方法的更新输出

接下来，我们将使用
requestrefererhandler
类中未在
requestrefererhandler接口中指定的方法。这不是一个好主意
interface SanitizerInterface
{
    public function sanitizeAuthor();
    public function sanitizeDate();
    public function sanitizeSearch();
    public function sanitizeTaxonomy();
}

abstract class AbstractSanitizer implements SanitizerInterface
{
    protected $handler;

    public function __construct() {}

    public function setHandler(RequestReferrerHandlerInterface $handler)
    {
        $this->handler = $handler;
    }   

    /* For this example we are saying that sanitizeDate(), sanitizeTaxonomy() and
     * sanitizeSearch() will be the same no matter what.  So let's implement them 
     * and leave the child classes to implement sanitizeAuthor(). 
     * 
     * Implement the details of the sanitizer function to fit your needs.
     */

    public function sanitizeDate()
    {
        if($this->handler !== null)
        {
            //Perform whatever tasks to sanitize the date
            $sanitized = strtoupper($this->handler->getDateReferrer());
            echo "Sanitize date -> switch to uppercase letters.\n";
            $this->handler->setDateReferrer($sanitized);
        }
    }

    public function sanitizeSearch()
    {
        if($this->handler !== null)
        {
            //Perform whatever tasks to sanitize the search
            $sanitized = strtolower($this->handler->getSearchReferrer());
            echo "Sanitize search -> switch to lowercase letters.\n";
            $this->handler->setSearchReferrer($sanitized);
        }
    }

    public function sanitizeTaxonomy()
    {
        if($this->handler !== null)
        {
            //Perform whatever tasks to sanitize the taxonomy
            $sanitized = str_replace(" ", "_", $this->handler->getTaxReferrer());
            echo "Sanitize Taxonomy -> convert spaces to underscores.\n";
            $this->handler->setTaxReferrer($sanitized);
        }
    }

}

interface RequestReferrerHandlerInterface
{
    public function hasAuthorReferrerValue();
    public function hasDateReferrerValue();
    public function hasSearchReferrerValue();
    public function hasTaxReferrerValue();
    public function getAuthorReferrer();
    public function getDateReferrer();
    public function getSearchReferrer();
    public function getTaxReferrer();
    public function setAuthorReferrer($author);
    public function setDateReferrer($date);
    public function setSearchReferrer($search);
    public function setTaxReferrer($tax);
}

class SanitizerForClassA extends AbstractSanitizer
{
    /* This class must provide an implementation for how ClassA will
     * handle the sanitizeAuthor() method.
     */

    public function sanitizeAuthor()
    {
        if($this->handler !== null)
        {
            //Perform whatever tasks to sanitize the for ClassA
            $sanitized = array("author" => $this->handler->getAuthorReferrer());
            echo "Sanitize author -> ClassA makes author an array.\n";
            $this->handler->setAuthorReferrer($sanitized);
        }   
    }
}

class SanitizerForClassB extends AbstractSanitizer
{
    /* This class must provide an implementation for how ClassB will
     * handle the sanitizeAuthor() method.
     */

    public function sanitizeAuthor()
    {
        if($this->handler !== null)
        {
            //Perform whatever tasks to sanitize the for ClassB
            $sanitized = new stdClass();
            $sanitized->author = $this->handler->getAuthorReferrer();
            echo "Sanitize author -> ClassB makes author an object property. \n";
            $this->handler->setAuthorReferrer($sanitized);
        }   
    }
}

interface SanitizableHandlerInterface
{       
    public function __construct(RequestReferrerHandlerInterface $handler, SanitizerInterface $sanitizer);
}

interface QueryVarsInterface extends SanitizableHandlerInterface
{
    public function queryVars();
}

interface QueryArgumentsInterface extends SanitizableHandlerInterface
{
    public function queryArguments();
}

class ClassA implements QueryArgumentsInterface
{
    private $handler;
    private $sanitizer;

    public function __construct(RequestReferrerHandlerInterface $handler, SanitizerInterface $sanitizer)
    {
        $this->handler = $handler;
        $this->sanitizer = $sanitizer;
        $this->sanitizer->setHandler($this->handler);
    }

    public function queryArguments() // Will be used in the controller class ClassC
    {
        $queryArgs = null;
        if($this->handler->hasAuthorReferrerValue())
        {
            $this->sanitizer->sanitizeAuthor();
            $queryArgs = $this->handler->getAuthorReferrer();
        }
        if($this->handler->hasDateReferrerValue())
        {
            $this->sanitizer->sanitizeDate();
            $queryArgs = $this->handler->getDateReferrer();
        }
        if($this->handler->hasSearchReferrerValue())
        {
            $this->sanitizer->sanitizeSearch();
            $queryArgs = $this->handler->getSearchReferrer();
        }
        if($this->handler->hasTaxReferrerValue())
        {
            $this->sanitizer->sanitizeTaxonomy();
            $queryArgs = $this->handler->getTaxReferrer();
        }
        return $queryArgs; //Will return null if all 4 conditions fail or return the value from the one that returns true
    }

}

class ClassB implements QueryVarsInterface
{
    private $handler;
    private $sanitizer;

    public function __construct(RequestReferrerHandlerInterface $handler, SanitizerInterface $sanitizer)
    {
        $this->handler = $handler;
        $this->sanitizer = $sanitizer;
        $this->sanitizer->setHandler($this->handler);       
    }

    public function queryVars() // Will be used in the controller class ClassC
    {
        $queryVars = null;
        if($this->handler->hasAuthorReferrerValue())
        {
            $this->sanitizer->sanitizeAuthor();
            $queryVars = $this->handler->getAuthorReferrer();
        }
        if($this->handler->hasDateReferrerValue())
        {
            $this->sanitizer->sanitizeDate();
            $queryVars = $this->handler->getDateReferrer();
        }
        if($this->handler->hasSearchReferrerValue())
        {
            $this->sanitizer->sanitizeSearch();
            $queryVars = $this->handler->getSearchReferrer();
        }
        if($this->handler->hasTaxReferrerValue())
        {
            $this->sanitizer->sanitizeTaxonomy();
            $queryVars = $this->handler->getTaxReferrer();
        }
        return $queryVars; //Will return null if all 4 conditions fail or return the value from the one that returns true
    }
}

class Controller
{
    public function __construct() {}

    public function doStuff(QueryArgumentsInterface $argsClass, QueryVarsInterface $varsClass)
    {
        var_dump($argsClass->queryArguments());
        var_dump($varsClass->queryVars());
    }
}

//TEST DRIVE

//Create a controller that will use the classes
$controller = new Controller();

//Now make use of your new shiny handlers and sanitizers
$controller->doStuff(
    new ClassA(new RequestReferrerHandler("Mark Twain", null, null, null), new SanitizerForClassA()), 
    new ClassB(new RequestReferrerHandler(null, "January 1st, 1999", null, null), new SanitizerForClassB())
);

$controller->doStuff(
    new ClassA(new RequestReferrerHandler(null, null, "OK Google Now!", null), new SanitizerForClassA()), 
    new ClassB(new RequestReferrerHandler(null, null, null, "Super Awesome Taxonomy Tables"), new SanitizerForClassB())
);

$controller->doStuff(
    new ClassA(new RequestReferrerHandler(null, "January 1st, 1999", null, null), new SanitizerForClassA()), 
    new ClassB(new RequestReferrerHandler("Mark Twain", null, null, null), new SanitizerForClassB())
);

$controller->doStuff(
    new ClassA(new RequestReferrerHandler(null, null, null, "Super Awesome Taxonomy Tables"), new SanitizerForClassA()), 
    new ClassB(new RequestReferrerHandler(null, null, "OK Google Now!", null), new SanitizerForClassB())
);

Sanitize author -> ClassA makes author an array.
array (size=1)
  'author' => string 'Mark Twain' (length=10)
Sanitize date -> switch to uppercase letters.
string 'JANUARY 1ST, 1999' (length=17)
Sanitize search -> switch to lowercase letters.
string 'ok google now!' (length=14)
Sanitize Taxonomy -> convert spaces to underscores.
string 'Super_Awesome_Taxonomy_Tables' (length=29)
Sanitize date -> switch to uppercase letters.
string 'JANUARY 1ST, 1999' (length=17)
Sanitize author -> ClassB makes author an object property.
object(stdClass)[15]
  public 'author' => string 'Mark Twain' (length=10)
Sanitize Taxonomy -> convert spaces to underscores.
string 'Super_Awesome_Taxonomy_Tables' (length=29)
Sanitize search -> switch to lowercase letters.
string 'ok google now!' (length=14)

    <?php

/*
 * INTERFACES
 */

interface RequestReferrerHandlerInterface
{
    public function hasAuthorReferrerValue();
    public function hasDateReferrerValue();
    public function hasSearchReferrerValue();
    public function hasTaxReferrerValue();
    public function getAuthorReferrer();
    public function getDateReferrer();
    public function getSearchReferrer();
    public function getTaxReferrer();
    public function setAuthorReferrer($author);
    public function setDateReferrer($date);
    public function setSearchReferrer($search);
    public function setTaxReferrer($tax);
}

interface SanitizerInterface
{
    public function sanitizeAuthor();
    public function sanitizeDate();
    public function sanitizeSearch();
    public function sanitizeTaxonomy();
}

interface SanitizableHandlerInterface
{       
    public function __construct(RequestReferrerHandlerInterface $handler, SanitizerInterface $sanitizer);
}

interface QueryVarsInterface extends SanitizableHandlerInterface
{
    public function queryVars();
}

interface QueryArgumentsInterface extends SanitizableHandlerInterface
{
    public function queryArguments();
}

/*
 * ABSTRACT CLASSES
 */

abstract class AbstractSanitizer implements SanitizerInterface
{
    protected $handler;

    public function __construct() {}

    public function setHandler(RequestReferrerHandlerInterface $handler)
    {
        $this->handler = $handler;
    }   

    /* For this example we are saying that sanitizeDate(), sanitizeTaxonomy() and
     * sanitizeSearch() will be the same no matter what.  So let's implement them 
     * and leave the child classes to implement sanitizeAuthor(). 
     * 
     * Implement the details of the sanitizer function to fit your needs.
     */

    public function sanitizeDate()
    {
        if($this->handler !== null)
        {
            //Perform whatever tasks to sanitize the date
            $sanitized = strtoupper($this->handler->getDateReferrer());
            echo "Sanitize date -> switch to uppercase letters.\n";
            $this->handler->setDateReferrer($sanitized);
        }
    }

    public function sanitizeSearch()
    {
        if($this->handler !== null)
        {
            //Perform whatever tasks to sanitize the search
            $sanitized = strtolower($this->handler->getSearchReferrer());
            echo "Sanitize search -> switch to lowercase letters.\n";
            $this->handler->setSearchReferrer($sanitized);
        }
    }

    public function sanitizeTaxonomy()
    {
        if($this->handler !== null)
        {
            //Perform whatever tasks to sanitize the taxonomy
            $sanitized = str_replace(" ", "_", $this->handler->getTaxReferrer());
            echo "Sanitize Taxonomy -> convert spaces to underscores.\n";
            $this->handler->setTaxReferrer($sanitized);
        }
    }

}

/*
 * CONCRETE CLASSES
 */

class RequestReferrerHandler implements RequestReferrerHandlerInterface
{
    private $author;
    private $date;
    private $search;
    private $tax;

    public function __construct($author = null, $date = null, $search = null, $tax = null)
    {
        $this->setAuthorReferrer($author);
        $this->setDateReferrer($date);
        $this->setSearchReferrer($search);
        $this->setTaxReferrer($tax);
    }

    public function hasAuthorReferrerValue()
    {
        return $this->author !== null ? true : false;
    }

    public function hasDateReferrerValue()
    {
        return $this->date !== null ? true : false;
    }

    public function hasSearchReferrerValue()
    {
        return $this->search !== null ? true : false;
    }

    public function hasTaxReferrerValue()
    {
        return $this->tax !== null ? true : false;
    }

    public function getAuthorReferrer()
    {
        return $this->author;
    }

    public function getDateReferrer()
    {
        return $this->date;
    }

    public function getSearchReferrer()
    {
        return $this->search;
    }

    public function getTaxReferrer()
    {
        return $this->tax;
    }

    public function setAuthorReferrer($author)
    {
        $this->author = $author;
    }

    public function setDateReferrer($date)
    {
        $this->date = $date;
    }

    public function setSearchReferrer($search)
    {
        $this->search = $search;
    }

    public function setTaxReferrer($tax)
    {
        $this->tax = $tax;
    }
}

class SanitizerForClassA extends AbstractSanitizer
{
    /* This class must provide an implementation for how ClassA will
     * handle the sanitizeAuthor() method.
     */

    public function sanitizeAuthor()
    {
        if($this->handler !== null)
        {
            //Perform whatever tasks to sanitize the for ClassA
            $sanitized = array("author" => $this->handler->getAuthorReferrer());
            echo "Sanitize author -> ClassA makes author an array.\n";
            $this->handler->setAuthorReferrer($sanitized);
        }   
    }
}

class SanitizerForClassB extends AbstractSanitizer
{
    /* This class must provide an implementation for how ClassB will
     * handle the sanitizeAuthor() method.
     */

    public function sanitizeAuthor()
    {
        if($this->handler !== null)
        {
            //Perform whatever tasks to sanitize the for ClassB
            $sanitized = new stdClass();
            $sanitized->author = $this->handler->getAuthorReferrer();
            echo "Sanitize author -> ClassB makes author an object property. \n";
            $this->handler->setAuthorReferrer($sanitized);
        }   
    }
}

class ClassA implements QueryArgumentsInterface
{
    private $handler;
    private $sanitizer;

    public function __construct(RequestReferrerHandlerInterface $handler, SanitizerInterface $sanitizer)
    {
        $this->handler = $handler;
        $this->sanitizer = $sanitizer;
        $this->sanitizer->setHandler($this->handler);
    }

    public function queryArguments() // Will be used in the controller class ClassC
    {
        $queryArgs = null;
        if($this->handler->hasAuthorReferrerValue())
        {
            $this->sanitizer->sanitizeAuthor();
            $queryArgs = $this->handler->getAuthorReferrer();
        }
        if($this->handler->hasDateReferrerValue())
        {
            $this->sanitizer->sanitizeDate();
            $queryArgs = $this->handler->getDateReferrer();
        }
        if($this->handler->hasSearchReferrerValue())
        {
            $this->sanitizer->sanitizeSearch();
            $queryArgs = $this->handler->getSearchReferrer();
        }
        if($this->handler->hasTaxReferrerValue())
        {
            $this->sanitizer->sanitizeTaxonomy();
            $queryArgs = $this->handler->getTaxReferrer();
        }
        return $queryArgs; //Will return null if all 4 conditions fail or return the value from the one that returns true
    }

}

class ClassB implements QueryVarsInterface
{
    private $handler;
    private $sanitizer;

    public function __construct(RequestReferrerHandlerInterface $handler, SanitizerInterface $sanitizer)
    {
        $this->handler = $handler;
        $this->sanitizer = $sanitizer;
        $this->sanitizer->setHandler($this->handler);       
    }

    public function queryVars() // Will be used in the controller class ClassC
    {
        $queryVars = null;
        if($this->handler->hasAuthorReferrerValue())
        {
            $this->sanitizer->sanitizeAuthor();
            $queryVars = $this->handler->getAuthorReferrer();
        }
        if($this->handler->hasDateReferrerValue())
        {
            $this->sanitizer->sanitizeDate();
            $queryVars = $this->handler->getDateReferrer();
        }
        if($this->handler->hasSearchReferrerValue())
        {
            $this->sanitizer->sanitizeSearch();
            $queryVars = $this->handler->getSearchReferrer();
        }
        if($this->handler->hasTaxReferrerValue())
        {
            $this->sanitizer->sanitizeTaxonomy();
            $queryVars = $this->handler->getTaxReferrer();
        }
        return $queryVars; //Will return null if all 4 conditions fail or return the value from the one that returns true
    }
}

class Controller
{
    public function __construct() {}

    public function doStuff(QueryArgumentsInterface $argsClass, QueryVarsInterface $varsClass)
    {
        var_dump($argsClass->queryArguments());
        var_dump($varsClass->queryVars());
    }
}

/*
 * TEST DRIVE
 */

//Create a controller that will use the classes
$controller = new Controller();

//Now make use of your new shiny handlers and sanitizers
$controller->doStuff(
    new ClassA(new RequestReferrerHandler("Mark Twain", null, null, null), new SanitizerForClassA()), 
    new ClassB(new RequestReferrerHandler(null, "January 1st, 1999", null, null), new SanitizerForClassB())
);

$controller->doStuff(
    new ClassA(new RequestReferrerHandler(null, null, "OK Google Now!", null), new SanitizerForClassA()), 
    new ClassB(new RequestReferrerHandler(null, null, null, "Super Awesome Taxonomy Tables"), new SanitizerForClassB())
);

$controller->doStuff(
    new ClassA(new RequestReferrerHandler(null, "January 1st, 1999", null, null), new SanitizerForClassA()), 
    new ClassB(new RequestReferrerHandler("Mark Twain", null, null, null), new SanitizerForClassB())
);

$controller->doStuff(
    new ClassA(new RequestReferrerHandler(null, null, null, "Super Awesome Taxonomy Tables"), new SanitizerForClassA()), 
    new ClassB(new RequestReferrerHandler(null, null, "OK Google Now!", null), new SanitizerForClassB())
);

// Composition
class Car implements VehicleInterface
{
    private $motor;
}

class Motor implements MotorInterface

// Inheritance
class Car extends MotorVehicle
{

}

// Composition
class Car implements VehicleInterface
{
    private $motor;
    private $movement;
}

class Motor implements MotorInterface

class Drive implements MovementInterface

// Inheritance
class Car extends MotorVehicle, DriveVehicle
{

}

class Car implements VehicleInterface
{
    private $motor;
}

class PetrolMotor implements MotorInterface

class DieselMotor implements MotorInterface

class Car implements VehicleInterface
{
    private $motor;

    public function __construct(MotorInterface $motor)
    {
        $this->motor = $motor;
    }
}

class PetrolMotor implements MotorInterface
{
}

class DieselMotor implements MotorInterface
{
}

$motor = new PetrolMotor();
$car = new Car($motor);

// Standard OOP
$car = new Car();
$buyer = new Person();
$store = new Store();

// Many solutions to buy a car!
$buyer->buy($car, $store);
// or
$store->sell($car, $buyer);
// or
// ...

// SOA
$car = new Car();
$buyer = new Person();
$store = new Store();

$saleHandler = new SaleHandler();
$saleHandler->sell($car, $buyer, $store);