PHP5 Exceptions

[iceomnia]

OK, so I need some more help.

In C# and other C languages, predefined methods throw excptions for you so all you have to do is catch them.

whereas in php, it seems, you have to throw your own.

try
		{
			if (!@include(self::MAIN_ABS_PATH . self::SITE_DIR . self::CLASS_DIR . "/db.class.php"))
				throw new Exception("Failed to load ".self::MAIN_ABS_PATH . self::SITE_DIR . self::CLASS_DIR . "/db.class.php");
			require(self::MAIN_ABS_PATH . self::SITE_DIR . self::CLASS_DIR . "/dbTables.class.php");
			require(self::MAIN_ABS_PATH . self::SITE_DIR . self::CLASS_DIR . "/dbArrays.class.php");
			require(self::MAIN_ABS_PATH . self::SITE_DIR . self::CLASS_DIR . "/utilities.class.php");
			require(self::MAIN_ABS_PATH . self::SITE_DIR . self::CLASS_DIR . "/products.class.php");
			require(self::MAIN_ABS_PATH . self::SITE_DIR . self::CLASS_DIR . "/encryption.class.php");
		}
		catch (Exception $e)
		{
			$error = "File: ".$e->getFile()." Line: ".$e->getLine();

		die( $error, $e->getMessage() );
		exit();
	}

OK, so this works. But when you include an invalid file with include but leave off the "@" you get an ERROR warning or whatever.

How do I capture this warning or error and put it into a variable, as using a "@" before a function eliminates it's E_ERROR level completely.

[laserlight]

This sounds interesting. From what I've found, you can trap such errors this way:

try
{
    $error = error_get_last();
    @include self::MAIN_ABS_PATH . self::SITE_DIR . self::CLASS_DIR . "/db.class.php";
    $last_error = error_get_last();
    if ($last_error !== $error)
    {
        throw new Exception('Failed to load: ' . $last_error['message']);
        $error = $last_error; // In case you want to trap more errors.
    }

require self::MAIN_ABS_PATH . self::SITE_DIR . self::CLASS_DIR . "/dbTables.class.php";
require self::MAIN_ABS_PATH . self::SITE_DIR . self::CLASS_DIR . "/dbArrays.class.php";
require self::MAIN_ABS_PATH . self::SITE_DIR . self::CLASS_DIR . "/utilities.class.php";
require self::MAIN_ABS_PATH . self::SITE_DIR . self::CLASS_DIR . "/products.class.php";
require self::MAIN_ABS_PATH . self::SITE_DIR . self::CLASS_DIR . "/encryption.class.php";
}
catch (Exception $e)
{
    $error_message = 'File: ' . $e->getFile() . "<br />\nLine: " . $e->getLine()
                   . "<br />\n" . $e->getMessage();

die($error_message);
}

Note that [man]error_get_last/man is only available since PHP 5.2.0, so it may not work on some recent PHP installations. Also, you do not need to suppress errors with the @ operator if you set display_errors to Off in php.ini.

[iceomnia]

Ah, yes... I undrstand that. Maybe I'm asking the wrong questions...

In c# you can simply do this:

try 
        { 
            include(self::MAIN_ABS_PATH . self::SITE_DIR . self::CLASS_DIR . "/db.class.php"); 
            require(self::MAIN_ABS_PATH . self::SITE_DIR . self::CLASS_DIR . "/dbTables.class.php"); 
            require(self::MAIN_ABS_PATH . self::SITE_DIR . self::CLASS_DIR . "/dbArrays.class.php"); 
            require(self::MAIN_ABS_PATH . self::SITE_DIR . self::CLASS_DIR . "/utilities.class.php"); 
            require(self::MAIN_ABS_PATH . self::SITE_DIR . self::CLASS_DIR . "/products.class.php"); 
            require(self::MAIN_ABS_PATH . self::SITE_DIR . self::CLASS_DIR . "/encryption.class.php"); 
        } 
        catch (Exception $e) 
        { 
            $error = "File: ".$e->getFile()." Line: ".$e->getLine(); 

        echo $e->getMessage();
        exit(); 
    }

... C# creates the Exception for you, all you have to do is handle it!

So I want one single exception to handle all usually "identical" errors in the try block.

How would that be done?

[laserlight]

So I want one single exception to handle all usually "identical" errors in the try block.

How would that be done?

You will have to repeat my example for each include/require.

Actually, there's a flaw: error_get_last() (and $php_errormsg, I believe) tracks the last even across scripts, so the check that the error was not identical may not be accurate.

In short, you are looking at a shortcoming of PHP 5 due to its PHP 4 legacy (where exceptions did not exist).

[iceomnia]

Ha ha, I have found another serious floor!

try
		{
$clasDir = MAIN_ABS_PATH . SITE_DIR . CLASS_DIR;
			if (!@include($clasDir . "/db.class.php"))
			{
				throw new Exception("Failed to load " . $clasDir . "/db.class.php");
			}

		unset($clasDir);
	}
	catch (Exception $e)
	{
		$error = "File: ".$e->getFile()." Line: ".$e->getLine();

		$this->debug("require", $error, $e->getMessage());
	}

By putting an "@" before the include, it actually stops any AND I MEAN ALL error reposting from any code in that file and anything that one includes too!

This is just getting worse and worse...

I have an idea! - don't use exceptions in PHP!

[laserlight]

By putting an "@" before the include, it actually stops any AND I MEAN ALL error reposting from any code in that file and anything that one includes too!

I do not recommend using the @ operator at all: as I mentioned earlier, just set display_errors to Off in php.ini on a production environment.

I have an idea! - don't use exceptions in PHP!

It's not the fault of exceptions. It is the fault of having to be backward compatible. Exceptions are a PHP 5 feature, but include is a language construct that has been around... forever.

[iceomnia]

include()

should simply return TRUE and false Bool.

Maybe in php 5.2.7 it would have the option to use it like this, to enable what I'm trying to achieve.

$boolResult = include('whatever.CLASS.php');

if ($boolResult == false)
{
    throw new Exception('Include didnt work');
}
catch(Exception $e)
{
    echo $e->__tostring();
}

That would be really simple...

You know, I do understand that php are trying to implement the Exception things, but php4 compatibility makes this impossible.

[laserlight]

Maybe in php 5.2.7 it would have the option to use it like this, to enable what I'm trying to achieve.

Oh dear, the mention of a future version of PHP made me check up an old link on Minutes PHP Developers Meeting for PHP 6, and the section on All non-fatal errors should become exceptions suggests a current workaround.

I should have played around with the old set_error_handler() instead of reaching for the newfangled error_get_last().

EDIT:
In other words, you can write:

<?php
function error_handler($type, $message)
{
    throw new Exception($message);
}

set_error_handler('error_handler');

try
{
    include 'whatever.class.php';
}
catch (Exception $e)
{
    echo $e->getMessage();
}
?>

[iceomnia]

Cool, so what if I'm doing this within a class?

Would it look something like this:

<?php

class whatever
{

function error_handler($type, $message)
{
    throw new Exception($message);
}


function __construct()
{
     set_error_handler(self::'error_handler');

 try
 {
     include 'whatever.class.php';
 }
 catch (Exception $e)
 {
     echo $e->getMessage();
 }
}


} // End class
?> 

Obviously that won't work, I can see it won't but what should it be?

[laserlight]

set_error_handler() works globally, so you should use a free function and set it globally.