Re: exceptions instead of errors

At 17:40 11.05.2003, Theo Spears wrote:

On Sunday 04 May 2003 20:48, Sterling Hughes wrote: Just a note that I'd really like to see this. One of the great things about exceptions will be: try { $m = mysql_connect("localhost", "user", "pass"); $sth = mysql_query("select bar from foo", $m); while ($row = mysql_fetch_array($sth)) {

    echo $row[0];

} mysql_close($m); } catch (exception $e) { echo $e->getMessage(); } This allows you to remove all the nasty if ($conn) could, and move your error handling into a singular place. I *really* would like this for internal functions. We could also make a new type of exception "internalexception," which a user has to specifically catch. This way unless you explictly specify that you want to catch an internalexception, it will default to just outputting an error message. Although this approach would certainly simplify handling errors it seems to me it would give everyone big problems when it comes to predicting the control flow of their programs. For example function db_connect ( $db_name ) { $link = mysql_connect(); if ( ! mysql_select_db( $db_name, $link ) ) {

    mysql_select_db ( BACKUP_DB_NAME, $link );

} } now, depending on whether you do try { db_connect ( 'foo' ); } catch (exception e) { } or just db_connect ( 'foo' ); The function will behave differently. Even if all new PHP5 code uses exceptions there is a lot of code which doesn't, and so the principles of information hiding say you would have to make sure any code which calls a function in a separate module has to make sure that function isn't inside a try{}catch{} block, and the only functions in the same module which are inside try{}catch{} blocks that catch internal exceptions don't call any functions in external modules. Personally I would prefer a system similar to the @ notation which suppresses error messages, possibly make %function() or similar cause the function to raise an exception. (The engine could handle this by silently dropping all exceptions from internal functions that weren't called with the relevant prefix).

The rule "try/catch = exception" would be easy enough to understand. Changing all code to use exceptions would also work since the bahaviour would fall back to the normal one if you missed to define a try/catch block. marcus