當物件屬性增多，逐一呼叫 Setter 方法顯得冗長。利用關聯陣列搭配建構子，可一次性傳入多組屬性值，大幅簡化物件初始化程式碼，也是後續整合資料庫資料的基礎模式。

傳統方式：逐一呼叫 Setter

<?php
$user = new User();
$user->setName('Kirupa');
$user->setJob('Engineer');
$user->setSchool('MIT');
$user->setHomeTown('Spanish Fort');
$user->setHomeState('Alabama');
// 5 個方法呼叫，程式碼冗長
?>

關聯陣列 + 建構子：一次注入多屬性

<?php
$attribs = [
    'name'      => 'Kirupa',
    'job'       => 'Engineer',
    'school'    => 'MIT',
    'homeTown'  => 'Spanish Fort',
    'homeState' => 'Alabama',
];

$kirupa = new User($attribs);

echo 'Name: '      . $kirupa->getName()      . '<br />';
echo 'Job: '       . $kirupa->getJob()       . '<br />';
echo 'School: '    . $kirupa->getSchool()    . '<br />';
echo 'Home Town: ' . $kirupa->getHomeTown()  . '<br />';
echo 'Home State: ' . $kirupa->getHomeState() . '<br />';

class User {
    private string $name = '';
    private string $job = '';
    private string $school = '';
    private string $homeTown = '';
    private string $homeState = '';
    
    // 建構子接收關聯陣列
    public function __construct(array $attribs = []) {
        $this->name      = $attribs['name']      ?? '';
        $this->job       = $attribs['job']       ?? '';
        $this->school    = $attribs['school']    ?? '';
        $this->homeTown  = $attribs['homeTown']  ?? '';
        $this->homeState = $attribs['homeState'] ?? '';
    }
    
    // Getter/Setter 略...
}
?>

優勢分析

• 程式碼簡潔：一行建立物件並設定所有屬性
• 彈性擴充：新增屬性只需修改建構子與陣列，呼叫端無需異動
• 資料庫整合天然契合：PDO::FETCH_ASSOC 直接回傳關聯陣列，可直接傳給建構子
• 可選參數支援：利用 ?? null 聯合運算子提供預設值

方法互動：衍生屬性計算

物件內部方法可互相呼叫，實作衍生邏輯（如州名轉縮寫）：

<?php
$attribs = [
    'name'      => 'Kirupa',
    'homeState' => 'Alabama',
];

$kirupa = new User($attribs);

echo 'Name: '         . $kirupa->getName()          . '<br />';
echo 'Home State: '   . $kirupa->getHomeState()     . '<br />';
echo 'State Abbr.: '  . $kirupa->getHomeStateAbbr() . '<br />'; // AL

class User {
    private string $name = '';
    private string $homeState = '';
    
    public function __construct(array $attribs = []) {
        $this->name      = $attribs['name']      ?? '';
        $this->homeState = $attribs['homeState'] ?? '';
    }
    
    public function getName(): string { return $this->name; }
    public function getHomeState(): string { return $this->homeState; }
    
    // 衍生方法：呼叫自身其他方法
    public function getHomeStateAbbr(): string {
        $abbr = States::$ABBRS[$this->getHomeState()] ?? 'Unknown';
        return $abbr;
    }
}

// 靜態類別儲存常態對照表
class States {
    public static array $ABBRS = [
        'Alabama' => 'AL',
        'Michigan' => 'MI',
        'New York' => 'NY',
        // 更多...
    ];
}
?>

靜態屬性與方法補充

• static 成員屬於類別而非實例，所有實例共享
• 存取方式：ClassName::$staticProp、ClassName::staticMethod()
• 常用於：設定值、快取、對照表、單例模式、工廠方法
• 命名慣例：全大寫底線分隔（如 $ABBRS、$DB_CONFIG）

進階：資料轉換與驗證

<?php
class User {
    private string $email = '';
    private \DateTime $birthDate;
    
    public function __construct(array $data = []) {
        // 建構子處理資料轉換與驗證
        $this->email = $data['email'] ?? '';
        
        if (isset($data['birth_date'])) {
            $this->birthDate = new \DateTime($data['birth_date']);
        }
    }
    
    public function getAge(): int {
        return $this->birthDate->diff(new \DateTime())->y;
    }
}
?>