<?php

interface NamedInterface {
  public function name(): string;
}

class WidgetClass implements NamedInterface {
  private $name;
  private $width;

  public function __construct(string $name, int $width) {
    $this->name = $name;
    $this->width = $width;
  }

  public function name(): string {
    return $this->name;
  }

  public function setWidth(int $arg) {
    $this->width = $arg;
  }
}

class FactoryClass {
  public function generate(): NamedInterface {
    $widget = new WidgetClass('top', 42);
    return $widget;
  }
}

$f = new FactoryClass();
$w = $f->generate();
$w->setWidth(42);