在PHP中重構這兩個非常相似的類的OO方式是什麼？

Question

我有這樣一類以下內容：

class DreamsImagesStore 
{ 
    public $table = 'dreams_images'; 

    public function insertNewDreamImage($dream_id, $pid) 
    { 
    try { 
     $values = array($dream_id, $pid); 
     $sth = $this->dbh->prepare("INSERT INTO {$this->table} 
           (dream_id, pid) 
           VALUES (?, ?)"); 
     if($sth->execute($values)) { 
     return true; 
     } 
    } catch(PDOException $e) { 
     $this->errorLogger($e); 
    } 
    } 
... 
} 

我將要實施一項名爲InterestsImagesStore新的類，其中這些類之間的唯一區別將是$table值，$dream_id將$interest_id和dream_id在SQL將是interest_id。

我知道有一個更好的方法來做到這一點，而且我將在未來實施類似的課程，這些課程的差異很小。

什麼是最好的面向對象的方式來重構我的代碼，以避免重複和增加可維護性？

Answer 1

創建ImagesStore基類：

class ImagesStore 
{ 
    // See comments about accessors below. 
    private $table; 
    private $id_column; 

    public function insertImage($id, $pid) { 
    try { 
     $values = array($id, $pid); 
     $table = $this->getTable(); 
     $id_column = $this->getIdColumn(); 
     $sth = $this->dbh->prepare("INSERT INTO {$table} ($id_column, pid) VALUES (?, ?)"); 
     if ($sth->execute($values)) { 
     return true; 
     } 
    } 
    catch (PDOException $e) { 
     $this->errorLogger($e); 
    } 
    } 

    protected function __construct($table, $id_column) { 
    $this->table = $table; 
    $this->id_column = $id_column; 
    } 

    // These accessors are only required if derived classes need access 
    // to $table and $id_column. Declaring the fields "private" and providing 
    // "protected" getters like this prevents the derived classes from 
    // modifying these values which might be a desirable property of these 
    // fields. 
    protected function getTable() {return $this->table;} 
    protected function getIdColumn() {return $this->id_column;} 

    // More implementation here... 
    // Initialize $dbh to something etc. 
    // Provide "errorLogger" method etc. 
} 

，創造DreamsImagesStore和InterestsImagesStore專業：

class DreamsImagesStore extends ImagesStore { 
    public function __construct() { 
    parent::__construct('dreams_images', 'dream_id'); 
    } 
} 

class InterestsImagesStore extends ImagesStore { 
    public function __construct() { 
    parent::__construct('interests_images', 'interest_id'); 
    } 
} 

最初的方法insertNewDreamImage可以被重命名爲insertImage因爲它實際上是比原來更普遍名字暗示。

請注意，ImagesStore也可以聲明爲abstract如果您想阻止它的直接實例化。

可以採用另一種方法是不從ImagesStore都懶得派生類，只是通過使__construct方法public並調用它，如下所示實例化它直接：

$dreamsImagesStore = new ImagesStore("dreams_images", "dream_id"); 

另一種方法也可能是在ImagesStore中實施靜態工廠方法。

Answer 2

使用由理查德·庫克創建ImagesStore類，這也可能發生：

function FactoryLoadImageStore($imageStoreType) 
{ 
    switch($imageStoreType) 
    { 
     case "Interests": 
      return new ImageStore('interests_images', 'interest_id'); 
     case "Dreams": 
      return new ImageStore('dreams_images', 'dreams_id'); 
     default: 
      throw new Exception("ImageStore type $imageStoreType not found") 
; } 

} 

，或者你甚至可以更大膽的嘗試和做類似

function FactoryLoadImageStore($imageStoreType) 
{ 
    $tableName = $imageStoreType . 's_images'; 
    $idColumnName = $imageStoreType . 's_id'; 
    $tableExists = false; 
    $sql= "Show tables like '$tableName' "; 
    foreach ($this->dbh->query($sql) as $row) 
    { 
     if ($row['tableName'] == $tableName) 
     { 
      $tableExists = true; 
      break; 
     } 
    } 
    if(!$tableExists) 
    { 
     throw new Exception ("No matching table exists for the requested image store $imageStoreType"); 
    } 

    return new ImageStore($tableName, $idColumnName); 
} 

電話如下

$dreamImageStore = ImageStore::FactoryLoadImageStore('dream');