PHPInterfaces.php

<?php

// Exemplo de refatoraço

interface Style {}
interface PptStyle extends Style {}
interface PdfStyle extends Style {}

class Style {
    // Propriedades    
}

class Ppt {
    public function __construct(Style $style) {}
}

// Exemplo
$style = new Style;
$ppt = (new Ppt($style))->genPPt();