Exemple de classe enregistrée comme gestionnaire de flux

L'exemple ci-dessous implémente un gestionnaire de protocole var:// qui permet d'écrire et lire une variable globale en utilisant les fonctions standard de fichier, telle que fread(). Le protocole var:// implémenté ci-dessous, va, à partir d'une URL "var://foo" accéder à la variable globale $GLOBALS["foo"].

Exemple #1 Un flux pour lire et écrire des variables globales

<?php

class VariableStream {
	var $position;
	var $varname;

	function stream_open($path, $mode, $options, &$opened_path)
	{
		$url = parse_url($path);
		$this->varname = $url["host"];
		$this->position = 0;

		return true;
	}

	function stream_read($count)
	{
		$ret = substr($GLOBALS[$this->varname], $this->position, $count);
		$this->position += strlen($ret);
		return $ret;
	}

	function stream_write($data)
	{
		$left = substr($GLOBALS[$this->varname], 0, $this->position);
		$right = substr($GLOBALS[$this->varname], $this->position + strlen($data));
		$GLOBALS[$this->varname] = $left . $data . $right;
		$this->position += strlen($data);
		return strlen($data);
	}

	function stream_tell()
	{
		return $this->position;
	}

	function stream_eof()
	{
		return $this->position >= strlen($GLOBALS[$this->varname]);
	}

	function stream_seek($offset, $whence)
	{
		switch ($whence) {
			case SEEK_SET:
				if ($offset < strlen($GLOBALS[$this->varname]) && $offset >= 0) {
					 $this->position = $offset;
					 return true;
				} else {
					 return false;
				}
				break;

			case SEEK_CUR:
				if ($offset >= 0) {
					 $this->position += $offset;
					 return true;
				} else {
					 return false;
				}
				break;

			case SEEK_END:
				if (strlen($GLOBALS[$this->varname]) + $offset >= 0) {
					 $this->position = strlen($GLOBALS[$this->varname]) + $offset;
					 return true;
				} else {
					 return false;
				}
				break;

			default:
				return false;
		}
	}

	function stream_metadata($path, $option, $var) 
	{
  if($option == STREAM_META_TOUCH) {
   $url = parse_url($path);
		 $varname = $url["host"];
   if(!isset($GLOBALS[$varname])) {
		  $GLOBALS[$varname] = '';
   }
   return true;
  }
  return false;
	}
}
stream_wrapper_register("var", "VariableStream")
	or die("Failed to register protocol");

$myvar = "";

$fp = fopen("var://myvar", "r+");

fwrite($fp, "line1\n");
fwrite($fp, "line2\n");
fwrite($fp, "line3\n");

rewind($fp);
while (!feof($fp)) {
	echo fgets($fp);
}
fclose($fp);
var_dump($myvar);

?>

L'exemple ci-dessus va afficher :

line1
line2
line3
string(18) "line1
line2
line3
"

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