你不能在一个PHP类中放入两个具有唯一参数签名的__construct函数。我想这样做:
class Student
{
protected $id;
protected $name;
// etc.
public function __construct($id){
$this->id = $id;
// other members are still uninitialized
}
public function __construct($row_from_database){
$this->id = $row_from_database->id;
$this->name = $row_from_database->name;
// etc.
}
}
PHP中最好的方法是什么?
更现代的方法:
你把独立的类混合成一个,实体和数据水合。
对于你的案例,你应该有两个类:
class Student
{
protected $id;
protected $name;
// etc.
}
class StudentHydrator
{
public function hydrate(Student $student, array $data){
$student->setId($data['id']);
if(isset($data['name')){
$student->setName($data['name']);
}
// etc. Can be replaced with foreach
return $student;
}
}
//usage
$hydrator = new StudentHydrator();
$student = $hydrator->hydrate(new Student(), ['id'=>4]);
$student2 = $hydrator->hydrate(new Student(), $rowFromDB);
另外请注意,您应该使用doctrine或其他已经提供自动实体水合的ORM。
你应该使用依赖注入来跳过手动创建像StudentHydrator这样的对象。
另一种选择是像这样在构造函数中使用默认参数
class Student {
private $id;
private $name;
//...
public function __construct($id, $row=array()) {
$this->id = $id;
foreach($row as $key => $value) $this->$key = $value;
}
}
这意味着你需要实例化一行像这样:$student = new student ($row['id'], $row),但保持你的构造函数漂亮和干净。
另一方面,如果你想利用多态性,那么你可以创建两个类,像这样:
class Student {
public function __construct($row) {
foreach($row as $key => $value) $this->$key = $value;
}
}
class EmptyStudent extends Student {
public function __construct($id) {
parent::__construct(array('id' => $id));
}
}
对于php7,我也比较了参数类型,你可以有两个具有相同数量的参数但不同类型的构造函数。
trait GenericConstructorOverloadTrait
{
/**
* @var array Constructors metadata
*/
private static $constructorsCache;
/**
* Generic constructor
* GenericConstructorOverloadTrait constructor.
*/
public function __construct()
{
$params = func_get_args();
$numParams = func_num_args();
$finish = false;
if(!self::$constructorsCache){
$class = new \ReflectionClass($this);
$constructors = array_filter($class->getMethods(),
function (\ReflectionMethod $method) {
return preg_match("/\_\_construct[0-9]+/",$method->getName());
});
self::$constructorsCache = $constructors;
}
else{
$constructors = self::$constructorsCache;
}
foreach($constructors as $constructor){
$reflectionParams = $constructor->getParameters();
if(count($reflectionParams) != $numParams){
continue;
}
$matched = true;
for($i=0; $i< $numParams; $i++){
if($reflectionParams[$i]->hasType()){
$type = $reflectionParams[$i]->getType()->__toString();
}
if(
!(
!$reflectionParams[$i]->hasType() ||
($reflectionParams[$i]->hasType() &&
is_object($params[$i]) &&
$params[$i] instanceof $type) ||
($reflectionParams[$i]->hasType() &&
$reflectionParams[$i]->getType()->__toString() ==
gettype($params[$i]))
)
) {
$matched = false;
break;
}
}
if($matched){
call_user_func_array(array($this,$constructor->getName()),
$params);
$finish = true;
break;
}
}
unset($constructor);
if(!$finish){
throw new \InvalidArgumentException("Cannot match construct by params");
}
}
}
使用它:
class MultiConstructorClass{
use GenericConstructorOverloadTrait;
private $param1;
private $param2;
private $param3;
public function __construct1($param1, array $param2)
{
$this->param1 = $param1;
$this->param2 = $param2;
}
public function __construct2($param1, array $param2, \DateTime $param3)
{
$this->__construct1($param1, $param2);
$this->param3 = $param3;
}
/**
* @return \DateTime
*/
public function getParam3()
{
return $this->param3;
}
/**
* @return array
*/
public function getParam2()
{
return $this->param2;
}
/**
* @return mixed
*/
public function getParam1()
{
return $this->param1;
}
}