Question

I’m looking to do this:

/* example filename: config_load.php */

$config_file = "c:\path\to\file.php";

function read_config($file = &$config_file)
{
$settings = array();
$doc = new DOMDocument('1.0');
$doc->load($file); 
$xpath = new DOMXPath($doc); 
$all=$xpath->query('appSettings/add');
foreach ($all as $setting) {$settings[$setting->getAttribute('key')]=$setting->getAttribute('value');}

return $settings;
}

/* end config_load.php */

So then when I actually call the file, it’d go like this –

require_once "config_load.php";
// $config_file = "c:\path\to\file2.php"; //could also do this
$config = read_config();

This way if I don’t specify a file, it’s going to read the default config file. I could also define $config_file anywhere before I make the function call. And someone without access to the config_load file need not worry about being able to load a different file, they can define it anywhere before they make the read_config() call.

Answer 1

It’s not possible:

The default value must be a constant expression, not (for example) a variable, a class member or a function call.

~ http://www.php.net/manual/en/functions.arguments.php#functions.arguments.default

However, you can get around it like this:

function read_config($file = false) {
    global $config_file;
    if ($file === false) $file = $config_file;

    $settings = array();
    $doc = new DOMDocument('1.0');
    $doc->load($file); 
    $xpath = new DOMXPath($doc); 
    $all=$xpath->query('appSettings/add');
    foreach ($all as $setting) {$settings[$setting->getAttribute('key')]=$setting->getAttribute('value');}

    return $settings;
}

or like this:

function read_config($file = false, $config_file = false) {
    if ($file === false && $config_file !== false) $file = $config_file;

    $settings = array();
    $doc = new DOMDocument('1.0');
    $doc->load($file); 
    $xpath = new DOMXPath($doc); 
    $all=$xpath->query('appSettings/add');
    foreach ($all as $setting) {$settings[$setting->getAttribute('key')]=$setting->getAttribute('value');}

    return $settings;
}