During the last project I worked on, before moving companies, I would often want to pass back more error information from methods than primitive types would allow. What I wanted was a PHP4 exception. You’ll need PHP 4.3.0 or above for this class to work.
N.B.: Where you see a back slash (\) I’ve put a line break for code formatting purposes, although this new line doesn’t occur in the code.
class Error {
var $message;
var $code;
var $file;
var $line;
var $trace;
function Error($message = null, $code = 0) {
$this->message = $message;
$this->code = $code;
$this->trace = (phpversion() >= 4.3) \
? debug_backtrace() : array();
}
function getMessage() {
return $this->message;
}
function getCode() {
return $this->code;
}
function getFile() {
return $this->trace['file'];
}
function getLine() {
return $this->trace['line'];
}
function getTrace() {
reset($this->trace);
return current($this->trace);
}
function getArgs() {
reset($this->trace);
$trace = current($this->trace);
return $trace['args'];
}
}
I then created the following function to identify when the Error class was returned:
function isError($result) {
return (is_a($result,'Error') ? true : false);
}
I would then use it like so:
class OrderDB {
...
function save() {
if (!$this->db->query( \
'UPDATE orders SET ... WHERE order_id = '. \
$this->order->getId())) {
return new Error( \
'Failed to update order '.$this->order->getId());
} else {
return true;
}
}
...
}
Mimicking a try catch block:
$saveResult = $orderDb->save();
if ($saveResult) {
...
} else if (isError($saveResult)) {
$logger = $this->locator->get('log');
$logger->log('Error occured in '. \
$saveResult->getFile().' on line '. \
$saveResult->getLine().': '.$saveResult->getMessage());
...
}
An obvious short coming of this solution is that every result must be checked whereas a true try catch statement will catch any exception thrown within the try block. On the plus side you can still extend the Error class and isError will recognise you’ve returned a child of the Error class.
Typically 2 minutes Googling reveals a beefed up PHP4 exception class.
