我像这样宣布课程:
class Foo{ public function __construct(){ echo 'Foo was created!';} }
class Foo2 extends Foo{ public function __construct(){ parent::__construct(); echo 'Foo2 was created!';} }
class Bar{
public function __construct(Foo $foo){ echo 'Bar was created!';}
}
在主代码中:
$foo2 = new Foo2();
$bar = new Bar($foo2);
主代码中出现此错误的原因是什么:
Fatal error: Default value for parameters with a class type hint can only be NULL
php版本:PHP5.3.2
--------------------------------------更新了----------------------------------------
namespace system\data{
include ('system.php');
use system;
class DBConnection implements system\IDisposable {
protected $serverName;
protected $userId;
protected $password;
protected $handler;
protected $isOpened;
/*
* create a new instance of DBConnection.
*/
public function __construct($server, $uid, $password) {
$this->isOpened = false;
$this->serverName = $server;
$this->userId = $uid;
$this->password = $password;
}
class DBCommand implements \system\IDisposable {
public function __construct(DBConnection $connection, int $type) {
$this->connection = $connection;
$this->queryType= $type;
}
}
文件:system.data.mysql.php
namespace system\data\mysql{
class MySqlCommand extends DBCommand {
public function __construct(data\DBConnection $connection, int $type = 0) {
parent::__construct($connection, $type);
}
}
class MySqlConnection extends DBConnection {
public function __construct($server, $uid, $password) {
parent::__construct($server, $uid, $password);
}
}
}
错误:
Fatal error: Default value for parameters with a class type hint can only be NULL in C:\Program Files\Apache Software Foundation\...\system.data.mysql.php on line 35(constructor declartion)
