function apply (Component $component)
  {
    if ($component->supportsProperties()) {
      if ($this->props)
        $component->props->applyDefaults ($this->props);
      if ($this->unset)
        foreach ($this->unset as $prop)
          unset ($component->props->$prop);
    }

    if ($this->content) {
      $component->removeChildren();
      Metadata::compile ($this->content, $component);
    }
    if ($this->prepend)
      Metadata::compile ($this->prepend, $component, true);
    if ($this->append)
      Metadata::compile ($this->append, $component);
  }