forefinger

set $php_admin_value "xcache.cacher=Off";
set $php_admin_value "$php_admin_value \n xcache.stat=Off";
set $php_admin_value "$php_admin_value \n xcache.optimizer Off";
fastcgi_param  PHP_ADMIN_VALUE $php_admin_value;

$var = create_function('','return false;');
var_dump($var, is_string($var));
// string(9) "lambda_1"
// bool(true)
$var = function() {return false;};
var_dump($var, is_string($var));
$var = function() {return false;};
var_dump($var, is_string($var));
// object(Closure)#1 (0) {
// }
// bool(false)

$var = create_function('','return false;');
var_dump($var, function_exists($var), function_exists(''.$var), function_exists(trim($var)));
// string(9) "lambda_1"
// bool(true)
// bool(true)
// bool(false)