Ejercicio en PHP

Company.php

<?php
namespace exercise;

class Company {
    use Xetter;

    private $name;
    private $employees = array();

    public function __construct() {
        $this->employees = new EmployeeCollection;
    }

    public function setName($name) {
        $this->name = $name;
    }

    public function getName() {
        return $this->name;
    }

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

        return $this;
    }

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

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

Designer.php

<?php
namespace exercise;

class Designer extends Employee {
    const TYPE_GRAPHIC = 'graphic';
    const TYPE_WEB = 'web';
}

Developer.php

<?php
namespace exercise;

class Developer extends Employee {
    const TYPE_PHP = 'php';
    const TYPE_PYTHON = 'python';
    const TYPE_JAVASCRIPT = 'javascript';
}

Employee.php

<?php
namespace exercise;

class Employee {
    use Xetter;

    private $name;
    private $lastname;
    private $age;
    private $type;

    public function setAge($age) {
        $this->age = $age;
        return $this;
    }

    public function getAge() {
        return $this->age;
    }

    public function setLastname($lastname) {
        $this->lastname = $lastname;
        return $this;
    }

    public function getLastname() {
        return $this->lastname;
    }

    public function setName($name) {
        $this->name = $name;
        return $this;
    }

    public function getName() {
        return $this->name;
    }
    public function setType($type) {
        $reflection = new \ReflectionClass(get_called_class());
        $allowedTypes = array_values($reflection->getConstants());

        if(array_search($type, $allowedTypes) === false) {
            throw new \ErrorException('Invalid type: ' .$type);
        }

        $this->type = $type;
        return $this;
    }

    public function getType() {
        return $this->type;
    }
}

EmployeeCollection.php

class EmployeeCollection extends \ArrayObject {
    public function each($fn) {
        foreach($this as $employee) {
            $fn($employee);
        }
    }

    public function reduce($fn, $memo) {
        $this->each(function($employee) use($fn, &$memo) {
            $memo = $fn($memo, $employee);
        });

        return $memo;
    }

    public function getAgeSum() {
        return $this->reduce(function($memo, $employee) {
            return $memo + $employee->getAge();
        }, 0);
    }

    public function getAgeMedia() {
        return $this->getAgeSum() / $this->count();
    }
}

usage.php

$summa = new Company;

$summa->name = 'Summa Solutions';

// Property not found: employees
try {
    $summa->employees = 1;
} catch (\Exception $e) {
    echo $e->getMessage() . '<br/>';
}

$valentin = new Developer;

// Using explicit setters
$valentin
        ->setName('Valentin')
        ->setLastname('Starck')
        ->setAge(25)
        ->setType(Developer::TYPE_JAVASCRIPT);

$summa->addEmployee($valentin);

$agustin = new Developer;

// Using __set
$agustin->name = 'Agustin';
$agustin->lastname = 'Didiego';
$agustin->age = 33;
$agustin->type = Developer::TYPE_PHP;

// throws "Invalid type: HTML"
try {
    $agustin->type = 'HTML';
} catch (\Exception $e) {
    echo $e->getMessage() . '<br/>';
}

$summa->addEmployee($agustin);

// throws Catchable fatal error: Argument 1 passed (...) must be an instance of exercise\Employee
//$summa->addEmployee(1);


echo $summa->getAgeMedia(); // 29

Xetter.php

<?php
namespace exercise;

trait Xetter {
    public function __set($name, $value) {
        $method = 'set' . ucfirst($name);

        if (method_exists($this, $method)) {
            return $this->{$method}($value);
        }

        throw new \ErrorException('Property not found: ' . $name);
    }

    public function __get($name) {
        $method = 'get' . ucfirst($name);

        if (method_exists($this, $method)) {
            return $this->{$method}();
        }

        throw new \ErrorException('Property not found: ' . $name);
    }
}