Question

我创建了两个非常基本的接口，名为ReaderInterface和WriterInterface，但是我已经从这个例子中删除了WriterInterface，因为没有必要说明我的难题。

ReaderInterface.php

interface ReaderInterface
{
    public function read();
}

我有一个名为Datatable的具体类：

Datatable.php

class Datatable
{
    protected $cols;
    protected $rows;

    protected $reader;

    public function __construct()
    {
        $this->cols = array();
        $this->rows = array();

        $this->reader = null;
    }

    public function setReader(ReaderInterface $reader)
    {
        $this->reader = $reader;
    }

    public function load()
    {
        //Contents to follow below.
    }
}

我实例化一个数据表实例，如下所示：

$db = new PDO("mysql:host=localhost;port=3306;dbname=test", "user", "pass"); //Let's pretend this is a good connection.

$datatable = new Datatable();
$datatable->setReader(new DatatableReader($db));
$datatable->load();

我的问题是关于实现DatatableReader，以便它可以从我传入的数据库中读取，并在我的Datatable对象中写入$this->cols和$this->rows。

我看到了两种方法。

1。依赖注入

class DatatableReader implements ReaderInterface
{
    protected $db;
    protected $datatable;

    public function __construct(Datatable &$datatable, PDO &$db)
    {
        $this->datatable = $datatable;
        $this->db = $db;
    }

    public function read()
    {
        //Execute prepared statement which returns 5 records.
        //Get the columns, and place them into an array.

        foreach ($columns as $col) {
            $this->datatable->addColumn($col); //Add a column to the datatable.
        }
    }
}

然后，我的Datatable::load()方法将实现为：

public function load()
{
    if ($this->reader != null)
        $this->reader->read();
}

2。从read（）返回弱的返回。

class DatatableReader implements ReaderInterface
{
    protected $db;

    public function __construct(PDO &$db)
    {
        $this->db = $db;
    }

    public function read()
    {
        //Execute prepared statement which returns 5 records.
        //Get the columns, and place them into an array.
        return $columns;
    }
}

然后我会调用我的load()方法，如下所示：

public function load()
{
    if ($this->reader != null) {
        $retval = $this->reader->read();

        //Do stuff with the array of information returned from the reader.
    }
}

问题

这两个选项中哪一个是最好的设计？
我有没有第三种选择？

Answer 1

我会选择选项2.使用选项1可以产生递归：DatatableReader包含对象Datatable，反之亦然。

选项1的另一个坏处是你滥用read方法写入另一个对象。只有具体实现（DatatableReader）知道该对象。实现接口的所有对象都应以相同的方式作出反应。

PHP的读写器接口

1 个答案: