验证构造函数中的参数

Question

I'm developing a library management system, and basically I have an abstract class "Reader" that extends to "students, teachers and people in general". My question is, I have a class "Requests" and I need to know which "Reader" request the book, to be able to validate this data:

"teachers can only request 10 books simultaneously, the students can only request 5 books in simultaneously and the public in general can oly request 2 books in simultaneously;"

"teachers can keep each book at maximum for 6 months, students for 5 days, and the general public for 1 month;"

"if a teacher has a book for more than three months and there is a need to request it, the teacher must be notified to return the book;"

How can I pass the three type of "Readers" in the __construct, to validate the above data.

class Requests
{
    protected $bookRequested;
    protected $teacher;
    protected $student;
    protected $public;
    protected $requestDate;
    protected $returnDate;

    public function __construct(Book $bookRequested, Teacher $teacher, Student $student, GeneralPublic $public)
    {
        $this->bookRequested = $bookRequested;
        $this->teacher = $teacher;
        $this->student = $student;
        $this->public = $public;
        $this->requestDate = date('Y-m-d H:i:s');
        $this->returnDate = date('Y-m-d H:i:s');
    }
}

Answer 1

I'm not sure why you need all three readers in same request, since only one of them is going to be involved in a given transaction. If you have this:

abstract class Reader {}
class Teacher extends Reader {}
class Student extends Reader {}
class GeneralPublic extends Reader {}

... then your constructor just needs one parameter, the base class:

public function __construct(Book $bookRequested, Reader $reader) {}

To configure stuff you can just create a property or method. If you opt for a method you get the plus of being able to make it abstract too:

abstract class Reader
{ 
    abstract public function getMaxBooks();
}

class Teacher extends Reader
{
    public function getMaxBooks() {
        return 10;
    }
}