(PHP 4, PHP 5, PHP 7, PHP 8)
xml_set_external_entity_ref_handler — Set up external entity reference handler
   Sets the external entity reference handler function for the XML parser
   parser.
  
parserThe XML parser.
handler
 If null is passed, the handler is reset to its default state.
 
An empty string will also reset the handler, however this is deprecated as of PHP 8.4.0.
 If handler is a callable,
 the callable is set as the handler.
 If handler is a string,
 it can be the name of a method of an object set with
 xml_set_object().
 
This is deprecated as of PHP 8.4.0.
As of PHP 8.4.0, the callable is checked to be valid while setting the handler, not when it is called. This means that xml_set_object() must be called prior to setting a method string as the callback. However, as this behaviour is also deprecated as of PHP 8.4.0, using a proper callable for the method is recommended instead.
The signature of the handler must be:
$parser,$open_entity_names,$base,$system_id,$public_idparseropen_entity_namesbasesystem_id) of the external entity.
          
         system_idpublic_id
       The handler should return true if the entity was handled,
       false otherwise.
       When returning false the XML parser will stop parsing and
       xml_get_error_code() will return
       XML_ERROR_EXTERNAL_ENTITY_HANDLING.
      
   Always returns true.
  
| Version | Description | 
|---|---|
| 8.4.0 | Passing a non-callable string to handleris now deprecated,
  use a proper callable for methods, ornullto reset the handler. | 
| 8.4.0 | The validity of handleras a callable
  is now checked when setting the handler instead of checking when calling it. | 
| 8.0.0 | parserexpects an XMLParser
  instance now; previously, a validxmlresource was expected. | 
| 7.3.0 | The return value of the handleris no longer
       ignored if the extension has been built against libxml. Formerly, the return
       value has been ignored, and parsing did never stop. | 
