Request simple wrapper

<?php
interface EscapeStrategy {
    public function escape($param);
}

class HTMLEscapeStrategy implements EscapeStrategy {
    public function escape($param) {
        return htmlentities($param);
    }
}

class Post {

    private $params = [];

    /**
     * @var EscapeStrategy
     */
    private $escapeStrategy;

    public function __construct(array $params = array(), EscapeStrategy $escapeStrategy) {
        $this->params = $params;
        $this->escapeStrategy = $escapeStrategy;
    }

    public function isEmpty() {
        return count($this->params) <= 0;
    }

    public function __get($name) {
        return $this->escapeStrategy->escape($this->params[$name]);
    }
}

$post = new Post($_POST, new HTMLEscapeStrategy());

?>

<form action="" method="POST">
    <input type="text" name="firstName" />
    <input type="submit" />
</form>

<?php if(!$post->isEmpty()): ?>
    <b><?= $post->firstName; ?></b>
<?php endif; ?>