Implications of use statements on overrides - JDocument Relates to: https://github.com/joomla/joomla-platform/blob/staging/libraries/joomla/document/document.php Example 1: uses dependency injection to pass in the Namespace and the Alias. This enables overriding the location of the class file so that the class can be overridden. The core HTML cl…

Document.php

namespace Joomla\Document;

class JDocument
{

public function __construct($options = array())
{
  if (array_key_exists('lineend', $options))
	{
		$this->setLineEnd($options['lineend']);
	}
// etc

	if (array_key_exists('namespace', $options))
	{
		$this->setNamespace($options['namespace']);
	}
}
public static function getInstance($type = 'html', $attributes = array())
{

// instead of hardcoding the path - as it is now
      
        $alias = $this->getNamespaceAlias;  // ex. Html
	$ns    = $this->getNamespace;       // ex. Joomla\Document\Html
        $class = $ns . '\' . $alias 

        return new $class();
}

//etc 

}

DocumentHardcoded.php

namespace Joomla\Document;

use Joomla\Document\Html\Html;

class JDocument
{

public function __construct($options = array())
{
  if (array_key_exists('lineend', $options))
  {
		$this->setLineEnd($options['lineend']);
	}
// etc

// do not use DI to pass in NS.
}
public static function getInstance($type = 'html', $attributes = array())
{

// this uses the hardcoded use statement to locate the file
      
        $class = $alias; 

        return new $class();
}

//etc 

}

Also, should get rid of those static instances - ignore them in the examples.