PHP 7.0.6 Released

    Exception::__construct

    (PHP 5 >= 5.1.0, PHP 7)

    Exception::__construct — Construct the exception

    Description

    public Exception::__construct ([ string $message = "" [, int $code = 0 [, Throwable $previous = NULL ]]] )

    Constructs the Exception.

    Parameters

    message

    The Exception message to throw.

    code

    The Exception code.

    previous

    The previous exception used for the exception chaining.

    Changelog

    Version Description
    7.0.0 The previous parameter is now of type Throwable.
    5.3.0 The previous parameter was added.

    Notes

    Note:

    The message is NOT binary safe.

    User Contributed Notes

    talksonweb at gmail dot com
    2 years ago
    For those that haven't done exception chaining. Here's an example.

    This allows you to add the previous exception to the next one and give yourself detailed information in the end as to what happened. This is useful in larger applications.

    <?php
    function theDatabaseObj(){
         if(     database_object ){
             return     database_object;
         }
         else{
             throw new     DatabaseException("Could not connect to the database");
         }
    }

    function     updateProfile( $userInfo ){
         try{
                 $db = theDatabaseObj();
                 $db->updateProfile();
         }
         catch(     DatabaseException $e ){
                 $message = "The user :" . $userInfo->username . " could not update his profile information";
                 /* notice the '$e'. I'm adding the previous exception  to this exception. I can later get a detailed view of
              where the problem began. Lastly, the number '12' is  an exception code. I can use this for categorizing my
             exceptions or don't use it at all. */
                 throw new MemberSettingsException($message,12,$e);
         }
    }

    try{
             updateProfile( $userInfo );
    }
    catch(     MemberSettingsException $e ){
             // this will give all information we have collected above.
             echo $e->getTraceAsString();
    }
    ?>
    mattsch at gmail dot com
    3 years ago
    Be aware that while $previous is quite useful in providing exception chaining and better traceability, none of the internal php exceptions (e.g. PDOException, ReflectionException, etc) are called internally within php with $previous in mind. 

    So if your code throws an exception, recovers from it, then catches one of these internal php exceptions, recovers from it and throws another exception, you will not know the first exception that was thrown when calling getPrevious.

    See: https://bugs.php.net/bug.php?id=63873
    mario dot mueller at twt dot de
    7 years ago
    This would be nice for handling ZendFramework Exceptions to your own framwork or CMS Exceptions:

    <?php
    try
    {
            $oZFResponse = $oZFHttpClient->request();
    }
    catch(    Zend_Http_Exception $exZFHttpEx)
    {
        throw new     Runtime_{$oZFHttpEx->getCode()}_Exception('some ErrorMailing Message', 500, $oZFHttpEx);
    }

    ?>

    Regards,
    Mario
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