PHP 7.2.0 Release Candidate 4 Released

Exception::__construct

(PHP 5 >= 5.1.0, PHP 7)

Exception::__construct例外を作成する

説明

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

例外を作成します。

パラメータ

message

スローする例外メッセージ。

code

例外コード。

previous

以前に使われた例外。例外の連結に使用します。

注意: Exception クラスのコンストラクタをサブクラス側から呼ぶと、 $code と $message が設定済みの場合はデフォルトの引数を無視します。

変更履歴

バージョン 説明
7.0.0 パラメータ previous の型が Throwable に変わりました。
5.3.0 previous パラメータが追加されました。

注意

注意:

message は、バイナリセーフ ではありません

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User Contributed Notes 3 notes

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23
talksonweb at gmail dot com
4 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();
}
?>
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2
mattsch at gmail dot com
4 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
up
0
ryan dot jentzsch at gmail dot com
11 months ago
Note that the code parameter is not the same as exit($code).
Also, the code argument in PHP 7 (possibly earlier versions) is cast to an int including negative values. The code below is completely valid:

<?php
try
{
    throw new \
Exception('Testing', -12.12);
}
catch (\
Exception $exception)
{
   
$code = $exception->getCode();
    if (
$code < 0)
    {
        exit(
abs($code));
    }
}
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