PHP: default as first option in switch statement?

Question

I've tested this and it works fine, but it looks... weird... to me. Should I be concerned that this is nonstandard form which will be dropped in a future version of PHP, or that it may stop working? I've always had a default case as the final case, never as the first case...

switch($kind)
{
    default:
     // The kind wasn't valid, set it to the default
     $kind = 'kind1';
     // and fall through:

    case 'kind1':
     // Do some stuff for kind 1 here
     break;

    case 'kind2':
     // do some stuff for kind2 here
     break;

    // [...]

    case 'kindn':
     // do some stuff for kindn here
     break;

}

// some more stuff that uses $kind here...

(In case it's not obvious what I'm trying to do is ensure $kind is valid, hence the default: case. But the switch also performs some operations, and then $kind is used after the switch as well. That's why default: falls through to the first case, and also sets $kind)

Suggestions? Is this normal/valid syntax?

Answer 1

Common practice is to define the default option as last option. But I see nothing wrong with your solution (if there is no predefined schema in your company how to layout your code)

Answer 2

it looks... weird... to me

Me too! But if it makes syntactical sense to do this, I think you are fine.

Answer 3

It is an unusual idiom, it causes a little pause when you're reading it, a moment of "huh?". It works, but most people would probably expect to find the default case at the end:

switch($kind)
{
    case 'kind2':
        // do some stuff for kind2 here
        break;

    // [...]

    case 'kindn':
        // do some stuff for kindn here
        break;]

    case 'kind1':
    default: 
        // Assume kind1
        $kind = 'kind1';

        break;

}

Answer 4

Kind of made me twinge at first, but that's just because we're not use to seeing things that way.

I would suggest that you document this highly, since some might call this "tricky" code. A noob or some future maintainer might come along and move it to the bottom where they're more comfortable with it and break the side-effect that is has being at the top.

Answer 5

I'd personally prefer to do

switch($kind)
{
    case 'kind2':
        // do some stuff for kind2 here
        break;

    // [...]

    case 'kindn':
        // do some stuff for kindn here
        break;

    case 'kind1':
    default:
        $kind = 'kind1'; // Redundant if it's already set as 'kind1', but that doesn't make any difference to the code.
        // Do some stuff for kind 1 here
        break;

}

Answer 6

This is how I'd probably do it... it's easy on the eye and keeps the functionality.

switch($kind)
{
    case 'kind1': default :
        // Do some stuff for kind 1 here
        break;
    case 'kind2':
        // do some stuff for kind2 here
        break;
    case 'kindn':
        // do some stuff for kindn here
        break;
}