Correct usage of "getInstance" and static methods in PHP?

Question

I'm a bit unclear on the correct use of static methods in PHP.

In the below scenario:

<?php

class Person 
{
    public $data;

    public function __construct($id) 
    {
        // Fetch record from our data source
        switch($id){
            case 1:
                $this->data = array('id'=>1, 'name'=>'Mike');
                break;
            case 2:
                $this->data = array('id'=>2, 'name'=>'Jennifer');
                break;
            default:
                exit('Record not found!');
        }
    }

    public function getName()
    {
        return $this->data['name'];
    }

    public static function getInstance($id)
    {
        return new self($id);
    }
} 

?>

I then output the names "Mike" and "Jennifer":

Example A

<?php 

foreach(array(1,2) as $id) 
    echo Person::getInstance($id)->getName(); 

?>

Example B

<?php 

foreach(array(1,2) as $id){
    $person = new Person($id);
    echo $person->getName();
}

?>

Either will print "MikeJennifer", but I was told Example A is wrong, "because Person is not a static class".

A class can't be declared "static" in PHP though, so why should it matter?

Answer 1

In "Emergent Design", Scott L Bain describes this as a first-step pattern in abstracting the creation of objects.

Day 1: No abstraction...

$person = new Person($id);

Day 2: a static method to build the object for you...

$person = Person::getPerson($id);

Why? Because now you only have one piece of code in your entire application that knows how to "new up" a person, rather than having many lines of code distributed amongst your entire application that have that knowledge. If you change how you build a person object in the future, you will be able to just change the getPerson static method.

Day 3+: you may decide to lean on an object builder or repository for creating the object. When you choose to do this, you could update your getPerson static method to use the builder / repository and once again the change happens in just one place.

This is called "cohesion". Having code where you can make changes without having to open lots of files.