As I was filling out a bug report, I realized why (speculation here) the constructor is final: so that functions like simplexml_load_file and simplexml_load_string can work. I imagine the PHP-ized code looks something like
<?php
function simplexml_load_file($filename, $class_name = "SimpleXMLElement", $options = 0, $ns = "", $is_prefix = false) {
return new $class_name($filename, $options, true, $ns, $is_prefix);
}
?>
If we were to use a different $class_name and change the constructor's definition these functions wouldn't work.
There's no easy, sensible solution that keeps simplexml_load_file and simplexml_load_string.
SimpleXMLElement::__construct
(PHP 5 >= 5.0.1)
SimpleXMLElement::__construct — Cria um novo objeto SimpleXMLElement
Descrição
Cria um novo objeto SimpleXMLElement.
Parâmetros
- data
-
Uma string XML bem formada ou um caminho ou URL para um documento XML se data_is_url é TRUE.
- options
-
Opcionalmente usado para especificar parâmetros adicionais Libxml.
- data_is_url
-
Por padrão, data_is_url é FALSE. Use TRUE para especificar que data é um caminho ou URL para um documento XML ao invés de string.
- ns
-
- is_prefix
-
Valor Retornado
Retorna um objeto SimpleXMLElement representando data .
Erros
Produz uma mensagem de erro E_WARNING para cada erro encontrado nos dados do XML e dispara uma exceção se os erros foram detectados.
Exemplos
Exemplo #1 Cria um objeto SimpleXMLElement
<?php
include 'example.php';
$sxe = new SimpleXMLElement($xmlstr);
echo $sxe->movie[0]->title;
?>
Exemplo #2 Cria um objeto SimpleXMLElement de uma URL
<?php
$sxe = new SimpleXMLElement('http://example.org/document.xml', NULL, TRUE);
echo $sxe->asXML();
?>
SimpleXMLElement::__construct
16-Aug-2009 10:52
06-Nov-2008 09:12
Note to tudor:
You can't override the constructor, but you can get around that with a simple static method:
<?php
class simpleXmlExtender extends SimpleXMLElement {
public static function _new($xml=NULL, $ns=NULL, $prefix=TRUE) {
// allows you to set certain option parameters to new default values,
// or automatically decide whether input data is a file or not
// optionally, you can save the object in an intermediate variable
// and peform other actions on/with it before returning it
return new simpleXmlExtender($xml, LIBXML_NOCDATA, file_exists($xml), $ns, $prefix);
}
}
$simpleXML = simpleXmlExtender::_new($xmldata);
?>
... it's a bit of a hack, but it works.
30-Sep-2008 05:42
A note about the undocumented parameters:
$ns (string): namespace prefix or URI
$is_prefix (bool): TRUE if $ns is a prefix, FALSE if it's a URI; defaults to FALSE
E.g.:
<?php
$xml_string = '<xml xmlns:foo='uuid:BDC6E3F0-6DA3-11d1-A2A3-00AA00C14882'>
<foo:bar>..................';
$a = new SimpleXMLElement($xml_string, NULL, FALSE, 'foo', TRUE);
$b = new SimpleXMLElement($xml_string, NULL, FALSE, 'uuid:BDC6E3F0-6DA3-11d1-A2A3-00AA00C14882', FALSE);
?>
However, I don't know exactly what these parameters are used for. They don't seem to be of much help when dealing with namespaces :-?
20-Nov-2007 09:35
This class is extendable, but it's too bad that its constructor cannot be overriden (PHP says it's a final method). Thus the class should be wrapped using the delegation principle rather that extended.

SimpleXMLElement->children()