如何在 PHP OOP 函数中传递对象数组

Question

您好，我有一个班级作为孩子，一个班级作为父母。 再次作为作家信息的一类。

在编写器类函数中传递两个对象（来自两个类子对象的对象）的数组时出现错误。我明白了：

Catchable fatal error: Argument 1 passed to PersonWriter::setData() must be an instance of
Person, array given, called in C:\xampp\htdocs\php\oop\book\Person.php on line 62 and
defined in C:\xampp\htdocs\php\oop\book\Person.php on line 40

我的问题是：

1. 我有一个子类，它是父类的直接后代。我使用父类类型创建方法。为什么不工作？
2. 如何解决这个问题？

这是我的代码：

<?php
    // Class Person
    class Person {
        public $name;
        public $gender;
        public $age;

        public function __construct($name, $gender, $age) {
            $this->name = $name;
            $this->gender = $gender;
            $this->age = $age;
        }

        public function getInfo() {
            $info = "Name : $this->name<br/>Gender : $this->gender<br/>Age : $this->age";   
            return $info;
        }
    }

    // Class Mahasiswa
    class Mahasiswa extends Person {
        public $npm;

        public function __construct($npm, $name, $gender, $age) {
            parent::__construct($name, $gender, $age);  
            $this->npm = $npm;
        }

        public function getInfo() {
            $info = "NPM : $this->npm<br/>";
            $info .= parent::getInfo();
            return $info;
        }
    }

    // Class PersonWriter
    class PersonWriter {
        private $persons = array();

        public function setData(Person $persons) {
            $this->persons[] =  $persons;
        }

        public function write() {
            $str = "";
            foreach ($this->persons as $person) {
                $str = "Name : $person->name<br/>";
                $str .= "Gender : $person->gender<br/>";
                $str .= "Age : $person->age<br/>";
            }

            echo $str;
        }
    }

    // Create 2 objects
    $mhs = new Mahasiswa("201143579091","Fandi Akhmad", "L", 21);
    $mhs2 = new Mahasiswa("201143579092","Annisya Ferronica", "P", 19);

    // Add objects to Array 
    $persons = array($mhs, $mhs2);

    $writer = new PersonWriter();
    $writer->setData($persons);
    $writer->write();
?>

答案：

1. 在下面检查为答案的示例代码中。
2. 哦，好吧，我明白了。我知道了解我的功能 setData(Person $persons) 因为在我的书中没有讲出解释。

现在我将 person 对象添加到数组中：

<?php ...
    $writer->setData($mhs);
    $writer->setData($mhs2);
?>

我像这样编辑了我的函数：

public function write() {
            $str = "";
            foreach ($this->persons as $person) {
                $str = "Name : $person->name<br/>";
                $str .= "Gender : $person->gender<br/>";
                $str .= "Age : $person->age<br/>";

                echo "<br/>";
                echo $str;
            }
        }

现在可以使用了。

Answer 1

这需要Person 而不是数组；

$writer->setData($persons);

这会起作用的；

$p = new Person("Jake", "male", 29);
$writer->setData($p);

这是因为setData 函数需要Person 对象；

public function setData(Person $persons) {
    $this->persons[] =  $persons;
}

如果你想让它接受一个数组，那么做；

public function setData(array $persons) {
    $this->persons[] =  $persons;
}

或者你可以通过删除提示让它接受你想要的任何东西；

public function setData($persons) {
    $this->persons[] =  $persons;
}

编辑

我假设这不是您的代码，因为如果是这样，那么在传入数组时它为什么会中断是非常明显的。请先了解 OO 的基础知识，然后再潜入两英尺并挣扎。该错误使问题很明显。这里解释一下；

// You are meant to pass in a Person object here, it then appends that
// to an existing array of Persons
public function setData(Person $persons) {
    $this->persons[] =  $persons;
}

// This array of Persons is then iterated over in this function, this is
// where line 48 is, 

public function write() {
    $str = "";
    // Here the foreach goes over the Persons array
    foreach ($this->persons as $person)
    {
        // But the $person objects are being accessed like objects using the
        // -> operator, so if you pass in an array it will fail because you do
        // no access an array using ->
        $str = "Name : $person->name<br/>";
        $str .= "Gender : $person->gender<br/>";
        $str .= "Age : $person->age<br/>";
    }

    echo $str;
}

您可以将这些行更改为以下内容以访问数组；

$str = "Name : " . $person['name'] . "<br/>";
$str .= "Gender : " . $person['gender'] . "<br/>";
$str .= "Age : " . $person['age'] . "<br/>";