What is the difference between setter methods and construct methods?

Question

If I have a setter and getter methods below :

<?php
class Name{
protected $first ;
public function setNameType($value) {
    $this->first = $value;
}
public function getNameType() {
    return $this->first;
}
}

$name = new Name;
$name->setNameType("My Name");
echo $name->getNameType();
?>

and a construct method like this

    <?php
class Name{
protected $first ;
public function __construct($value) {
    $this->first = $value;
}
public function getNameType() {
    return $this->first;
}
}

$name = new Name("My Name");
echo $name->getNameType();
?>

Can I use the two interchangeably at all times or is there situations where one will be most prefered over the other ?

Answer 1

There is also some great explaination about your question: http://www.potstuck.com/2009/01/08/php-dependency-injection/

Answer 2

Try this website. It explains all with examples. http://ralphschindler.com/2012/03/09/php-constructor-best-practices-and-the-prototype-pattern

Answer 3

Generally you would use constructors to set values if your class cannot exist or doesn't make sense without the value. If the value is allowed to be changed, than add a setter. If it should never be changed after construction, then don't add a setter.

Answer 4

An example code:

class Book {

    public function __construct() {

        $registry  = RegistrySingleton::getInstance();
        $this->_database = $registry->database;

        // or

        global $databaseConnection;
        $this->_database = $database;
    }

}

---

class Book {

    private $_databaseConnection;

    public function __construct() { }

    public function setDatabaseConnection($databaseConnection) {
        $this->_databaseConnection = $databaseConnection;
    }

}

---

$book = new Book();
$book->setDatabase($databaseConnection);

---

$book = new Book($databaseConnection, $configFile);

---

$book = new Book();
$book->setDatabase($databaseConnection);
$book->setConfigFile($configFile);

---

class Container {

    public static $_database;

    public static function makeBook() {

        $book = new Book();
        $book->setDatabase(self::$_database);
        // more injection...

        return $book;
    }

}

And then:

$book = Container::makeBook();