from scratch object-oriented recreation based on the functional paradigm.

from-scratch-oop.php

<?php

$class = call_user_func(function () {    
    $objects = [];

    return function() use (&$objects) {
    	return (object) [
	        'instanceof' => function($object) use (&$objects) {
	            return in_array($object, $objects);
	        },
	        'construtor' => function() use (&$objects) {
	            $private = (object) [
	            	'name' => '',
	            	'set_name' => fn ($self, $new_name) => $self->name = $new_name,
	            	'hello' => fn ($self) => print("hello {$self->name}!\n"),
	            ];
	
	            $public = fn () => (object) [
	                'set_name' => fn($new_name) => call_user_func($private->set_name, $private, $new_name),
	                'hello' => fn() => call_user_func($private->hello, $private),
	            ];
	
	            $objects[] = $public;
	
	            return $public;
	        }
	    ];
	};
});

$my_obj = call_user_func(call_user_func($class)->construtor);
call_user_func(call_user_func($my_obj)->set_name, 'Dornelles');

$my_obj2 = call_user_func(call_user_func($class)->construtor);
call_user_func(call_user_func($my_obj2)->set_name, 'Cristian');

call_user_func(call_user_func($my_obj)->hello);
call_user_func(call_user_func($my_obj2)->hello);

var_dump(call_user_func(call_user_func($class)->instanceof, $my_obj));
var_dump(call_user_func(call_user_func($class)->instanceof, $my_obj2));

alternative syntax

$my_obj = ($class()->construtor)();
($my_obj()->set_name)('Dornelles');

$my_obj2 = ($class()->construtor)();
($my_obj2()->set_name)('Cristian');

($my_obj()->hello)();
($my_obj2()->hello)();

var_dump(($class()->instanceof)($my_obj));
var_dump(($class()->instanceof)($my_obj2));

Output

hello Dornelles!
hello Cristian!
bool(true)
bool(true)