Re: [RFC] Disallow multiple default blocks in a single switch statement

Ferenc Kovacs wrote (on 13/08/2014):

I think you misunderstood that part, I was thinking about a state machine like this: 1. function doStuff(){ 2. switch($state){ 3. case OPENDOOR: 4. if(!opendoor()){ 5. break;

 6.       }
 7.     $state = SITDOWN;

8. case SITDOWN: 9. if(!sitdown()){ 10. break;

11.       }
12.     $state = SIPWHISKEY;

13. case SIPWHISKEY:

14.       sipwhiskey();

15. } 16. } where you modify the switch variable in one case and fall through into another. as I mentioned I don't have a reasonable use-case for multiple defaults, but I can see some for multiple case labels in general, and I don't think that it is better to have different behavior for case and default in this regard.

The assignments to $state in that code do not make any difference to execution, control simply flows forwards whenever there is no "break". $state is only tested once, to select the initial label to jump to, so no amount of reassigning it, or adding duplicate labels, can ever cause a second jump. I'm tempted to write a PHP script that emulates the switch execution by building a set of if and goto statements, which might make some of this behaviour clearer (not just for this discussion, but for other confusion I've seen elsewhere), but I don't have time right now.