Catching multiple exception types in one catch block

I'd like a cleaner way to obtain the following functionality, to catch AError and BError in one block:

try
{
    /* something */
}
catch( AError, BError $e )
{
    handler1( $e )
}
catch( Exception $e )
{
    handler2( $e )
}

Is there any way to do this? Or do I have to catch them separately?

AError and Berror have a shared base class, but they also share it with other types that I'd like to fall through to handler2, so I can't just catch the base class.

Solution 1:

Update:

As of PHP 7.1, this is available.

The syntax is:

try
{
    // Some code...
}
catch(AError | BError $e)
{
    // Handle exceptions
}
catch(Exception $e)
{
    // Handle the general case
}

Docs: https://www.php.net/manual/en/language.exceptions.php#example-294

RFC: https://wiki.php.net/rfc/multiple-catch

Commit: https://github.com/php/php-src/commit/0aed2cc2a440e7be17552cc669d71fdd24d1204a

For PHP before 7.1:

Despite what these other answers say, you can catch AError and BError in the same block (it is somewhat easier if you are the one defining the exceptions). Even given that there are exceptions you want to "fall through", you should still be able to define a hierarchy to match your needs.

abstract class MyExceptions extends Exception {}

abstract class LetterError extends MyExceptions {}

class AError extends LetterError {}

class BError extends LetterError {}

Then:

catch(LetterError $e){
    //voodoo
}

As you can see here and here, even the SPL default exceptions have a hierarchy you can leverage. Additionally, as stated in the PHP Manual:

When an exception is thrown, code following the statement will not be executed, and PHP will attempt to find the first matching catch block.

This means you could also have

class CError extends LetterError {}

which you need to handle differently than AError or BError, so your catch statement would look like this:

catch(CError $e){
    //voodoo
}
catch(LetterError $e){
    //voodoo
}

If you had the case where there were twenty or more exceptions that legitimately belonged under the same superclass, and you needed to handle five (or whatever large-ish group) of them one way and the rest the other, you can STILL do this.

interface Group1 {}

class AError extends LetterError implements Group1 {}

class BError extends LetterError implements Group1 {}

And then:

catch (Group1 $e) {}

Using OOP when it comes to exceptions is very powerful. Using things like get_class or instanceof are hacks, and should be avoided if possible.

Another solution I would like to add is putting the exception handling functionality in its own method.

You could have

function handleExceptionMethod1(Exception $e)
{
    //voodoo
}

function handleExceptionMethod2(Exception $e)
{
    //voodoo
}

Assuming there is absolutely no way you can control exception class hierarchies or interfaces (and there almost always will be a way), you can do the following:

try
{
    stuff()
}
catch(ExceptionA $e)
{
    $this->handleExceptionMethod1($e);
}
catch(ExceptionB $e)
{
    $this->handleExceptionMethod1($e);
}
catch(ExceptionC $e)
{
    $this->handleExceptionMethod1($e);
}
catch(Exception $e)
{
    $this->handleExceptionMethod2($e);
}

In this way, you are still have a only single code location you have to modify if your exception handling mechanism needs to change, and you are working within the general constructs of OOP.

Solution 2:

In PHP >= 7.1 this is possible. See this answer.

If you can modify the exceptions, use this answer.

If you can't, you could try catching all with Exception and then check which exception was thrown with instanceof.

try
{
    /* something */
}
catch( Exception $e )
{
    if ($e instanceof AError OR $e instanceof BError) {
       // It's either an A or B exception.
    } else {
        // Keep throwing it.
        throw $e;
    }
}

But it would probably be better to use multiple catch blocks as described in aforementioned answer.

try
{
    /* something */
}
catch( AError $e )
{
   handler1( $e );
}
catch ( BError $b )
{
   handler2( $e );
}

Solution 3:

Coming in PHP 7.1 is the ability to catch multiple types.

So that this:

<?php
try {
    /* ... */
} catch (FirstException $ex) {
    $this->manageException($ex);
} catch (SecondException $ex) {
    $this->manageException($ex);
}
?>

and

<?php
try {

} catch (FirstException | SecondException $ex) {
    $this->manageException($ex);
}
?>

are functionally equivalent.