使用php oop的类中的class对象

Question

I am not even sure how to ask. I do this all the time in C# but for the life of me I cannot find any decent examples in PHP. Can you help?

What I am trying to do is for example. Say I have a class called Company who has many Employees.

I want to be able to store all the employees in the company class then later when I iterate through the Company object I need to be able to iterate through all the employees that are assigned to that company and I am having a heck of a time trying to find a straight forward example.

I can populate it, but fro the life of me I cant loop through the Employees. I know I am doing something wrong but cannot figure it out. Here is what I have for example.

Employee

This could be completely wrong for all I know as getting the data back out.

    class Employee
    {
        private $first;
        private $last;

        public function __construct($first = null, $last = null)
        {
            if(isset ($first))
                $this->first = $first;

            if(isset ($last))
                $this->last = $last;
        }

        public function getEmployee()
        {
            return Employee($this->first, $this->last);
        }

        public function getFirst()
        {
            return $this->first;
        }

        public function getLast()
        {
            return $this->first;
        }
    }

Company has an array of employees.

In c# I would use something like a generic

    public List<Employee> Employees {get;set;}

Then in the constructor I would do something like

    Employees = new List<Employee>();

Then I could do something like

    foreach(var x in Customer.Employees)
            x.first;

That is what I am kind of trying to do.

    class Company
    {
        private $companyName;

        private $employees;


        public function __construct($nameOfCompany)
        {
            $this->companyName = $nameOfCompany;               
        }

        public function setEmployee(Employee $employee)
        {
            $this->employees[] = $employee;
        }

        public function getCompanyName()
        {
            return $this->companyName;
        }

        public function setCompanyName($nameOfCompany)
        {
            $this->companyName = $nameOfCompany;
        }

        public function getEmployees()
        {
            return $this->employees;
        }
    }

Create and populate

    $c = new Company("Test");
    $c->setEmployee(new Employee('A','B'));
    $c->setEmployee(new Employee('C','D'));
    $c->setEmployee(new Employee('E','F'));

Up until this point all is well.

To get the name of the company no problem.

    echo $c->getCompanyName();

    echo "<PRE>";
    print_r($c);
    echo "</PRE>";

But how do I loop through the employees?

I want to be able to do something like cast Companies employees in a loop to a single Employee then do something like

    foreach(customers employees)
           echo Employee->getFirst, etc...

Can someone please provide some guidance?

Thanks

Answer 1

version 1: explicit getter method

<?php
class Employee
{
  private $first;
  private $last;

  public function __construct($first = null, $last = null)
  {
    if(isset ($first))
    $this->first = $first;

    if(isset ($last))
    $this->last = $last;
  }

  public function getFirst()
  {
    return $this->first;
  }

  public function getLast()
  {
    return $this->first;
  }
}

class Company
{
  private $companyName;
  private $employees;

  public function __construct($nameOfCompany)
  {
    $this->companyName = $nameOfCompany;
  }

  public function addEmployee(Employee $employee)
  {
    $this->employees[] = $employee;
  }

  public function getCompanyName()
  {
    return $this->companyName;
  }

  public function getEmployees()
  {
    return $this->employees;
  }
}

$company = new Company('ACME');
$company->addEmployee(new Employee('A', 'A'));
$company->addEmployee(new Employee('B', 'B'));
$company->addEmployee(new Employee('C', 'C'));

foreach( $company->getEmployees() as $e ) {
  echo $e->getFirst(), "\n";
}

version 2: using __get

class Company
{
  private $companyName;
  private $employees;

  public function __construct($nameOfCompany)
  {
    $this->companyName = $nameOfCompany;
  }

  public function addEmployee(Employee $employee)
  {
    $this->employees[] = $employee;
  }

  public function __get($name) {
     // this will allow access to any member of the class
     // so you might want to test access first
     if ( isset($this->$name) ) {
       return $this->$name;
     }
   }

}

$company = new Company('ACME');
$company->addEmployee(new Employee('A', 'A'));
$company->addEmployee(new Employee('B', 'B'));
$company->addEmployee(new Employee('C', 'C'));

foreach( $company->employees as $e ) {
  echo $e->getFirst(), "\n";
}

$company = new Company('ACME');
$company->addEmployee(new Employee('A', 'A'));
$company->addEmployee(new Employee('B', 'B'));
$company->addEmployee(new Employee('C', 'C'));

foreach( $company->employees as $e ) {
  echo $e->getFirst(), "\n";
}

Answer 2

foreach ($company->getEmployees() as $emp) {
    //do something with $emp
}

See foreach .

One note:

    public function __construct($first = null, $last = null)
    {
        if(isset ($first))
            $this->first = $first;

        if(isset ($last))
            $this->last = $last;
    }

is exactly the same as

    public function __construct($first = null, $last = null)
    {
        $this->first = $first;
        $this->last = $last;
    }

because the fields first and last , having no initializer, are initialized to null . isset , in your case, only checks if the argument's null, since it's guaranteed to be set (it's an argument).

Answer 3

PHP has something called the PHP Standard Library built into the language. The PHP Standard Library comes with a number of interfaces that allow you to implement certain core language functionality into your own defined objects. Once of these is the iterator interface. Define a class that implements this interface, and then write an implementation that will allow your object to do what you want when it's placed in a foreach loop.

Also, depending on the semantic you're after, you could just as easily do a

foreach($company->getEmployees() as $employee)
{
    var_dump($employee);
}

The getEmployees method will only be called once.