[RESOLVED] declare a global variable as default

[roseplant]

In this code $system_settings is declared in an included file, hence the "global $systemsettings" in the body of the function. But why does this not work in the function declaration when trying to use a global function as default?

function db_connect($database = global $system_settings['defaultdatabase']) {
	global $database_connected;
	if (!$database_connected) {
		global $system_settings;

	$link1 = mysql_connect($system_settings['db_server'],$system_settings['db_username'],$system_settings['db_password']);

	if ($link1)
		$database_connected = 1;
	else
		die('cause of death: Could not connect to database');


	mysql_select_db($database, $link1);
}
}

[Rodney_H_]

Hi, I see two things that strike me right of the bat as being incorrect in reference to your first line of code:

i) You cannot use "global" when supplying a default argument value like that

ii) You cannot use a "variable" when supplying a default argument value either.

So, if I am thinking clearly here, you may have to rewrite your first line to something like this:

<?php
function db_connect($dbname, $dbhost, $dbuser, $dbpass) {

global $sql;

if (!$sql) {
	$sql = mysql_connect($dbhost, $dbuser, $dbpass) 
		   or die('Cause of death: Could not connect to ' . $dbhost);	
}

$db = mysql_select_db($dbname, $link1)
	  or die('Cause of death: Could not select ' . $dbhost);
}
?>

EDIT: If this is wrong, I apologize! LOL!!! ME NEED COFFEE!!!

[roseplant]

ok i understand. absolutely no way to use a variable as a default variable then - ill just have to do it the traditional way like ur code

[MarkR]

I don't think you can use anything except a constant as a default for a formal parameter.

Any easy way around this, is to the use "false" as the default value of the parameter, and check in the body of the function:

function DoSomeStuff($param = FALSE) {
  if ($param === FALSE) {
    // Set $param from some default value, somehow
  }
  // rest of function ...
}

Mark

[bpat1434]

Change this:

function db_connect($database = global $system_settings['defaultdatabase']) {

to this:

function db_connect($database=$system_settings['defaultdatabase']) {

And if the user forgets to input a string for $database, then the $system_settings['defaultdatabase'] value will be used, as long as the function has readability to the $system_settings array.

[Rodney_H_]

bpat1434 wrote:

Change this:

function db_connect($database = global $system_settings['defaultdatabase']) {

to this:

function db_connect($database=$system_settings['defaultdatabase']) {

... that produces the following error:

Parse error: syntax error, unexpected T_VARIABLE in C:\wamp\www\sandbox_RECYCLE\test.php on line 2

[roseplant]

yeah i get that error too. I tried that solution first, adding the global as u see in my posted example was just a last-straw attempt to get it to work.

[bradgrafelman]

Here is a workaround using constants:

global $system_settings;
define('defaultdatabase', $system_settings['defaultdatabase']);

function db_connect($database=defaultdatabase) { 

[MarkR]

I preferred my solution. Don't define a constant. Don't try to do something which PHP syntax doesn't support. Just have a "magic" value for the parameter (I usually use FALSE), and test it with === (three equals), substituting the appropriate default.

Mark

[bradgrafelman]

Agreed.

I had just never run into the fact that you couldn't use a variable as a default value and was curious if you could use constants and whatnot as well.

I've always used the 'FALSE' method, so definitely go with that.

[roseplant]

bradgrafelman said:
Here is a workaround using constants

Looks like a decent solution to me - I always leap right over the simplest solutions :p.

Thanks for your help.

[Rodney_H_]

One last thought here, and I hope it makes sense:

<?php
// create keyed array of DB parameters
$dbparams['host'] = 'localhost';
$dbparams['user'] = 'my_username';
$dbparams['pass'] = 'my_password';
$dbparams['db_name'] = 'my_db';


// define function
function db_connect($db_params) { // db parameters array as argument

global $connect;

if(!$connect)
{
	$connect = mysql_connect($db_params['host'], $db_params['user'], $db_params['pass']) 
	          or die('Could not connect to database.');
	$db = mysql_select_db($db_params['db_name']) 
	          or die('Could not select database.');
}

}

// call function
$database_connected = db_connect($dbparams);

?>

[bradgrafelman]

roseplant wrote:

Looks like a decent solution to me - I always leap right over the simplest solutions :p.

Thanks for your help.

As I said, using Mark's method would be better, though either way is fine I suppose.