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Date: Sun, 20 Oct 2019 09:01:22 +0200
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Subject: Re: [PHP-DEV] Adding explicit intent for SWITCH/CASE fall through?
From: alec@alec.pl ("A.L.E.C")

On 10/20/19 2:39 AM, Mike Schinkel wrote:
>> case X:
>> 	if (something) {
>> 		fallthrough;
>>        }
>> 	something-else;
>> 	break;
>> case Y: ....
> 
> Interesting. 
> 
> What would you expect this to do?  It is not intuitively obvious to me.

Directly jump to the next `case` (as `goto` would do).

Also, fallthrough probably shouldn't be just a no-op, it should be jump. Consider this code

case X:
   fallthrough;
   break;
case Y:

It should be clear what would happen in such cases.

>> Then, don't we need a way to jump outside of the whole switch statement? Ah, there's `goto` already. So, maybe extend `goto` somehow?
> 
> Is that not what `break` is for?

Right. I was too much on throwing new ideas that I missed that some are already
implemented ;). The point was that fallthrough with these added functionality mentioned
above would be very close to `goto`. On the other hand:

case X:
   goto next; // or goto case; ?
case Y:

sounds worse than:

case X:
   fallthrough;
case Y:

or

case X:
   pass;
case Y:

> The fact a potential feature is a no-op does not discredit it for me; instead I focus on the benefits the proposed feature can provide. 
> 
> In this case the benefits would be to alerting developer when they accidentally omit instructions to PHP of their intentions. And that seems to me to be something (almost?) everyone would want to see embraced?  Clearly* PHPStan and many Linux developers would like the same[1][2].

Maybe if it was a feature (keyword) that could be useful in other places not only in
switch...

I proposed "pass" because it might have some uses out of switch (nothing comes to my mind,
though right now) and because "fallthrough" is kinda hard word for non-native speakers.

"pass" exists in Python. https://docs.python.org/2.0/ref/pass.html

>> It might be not useful enough to justify a BC break.

That was my intention, to find more value in a new feature to justify BC break.

-- 
Aleksander 'A.L.E.C' Machniak
Kolab Groupware Developer         [http://kolab.org]
Roundcube Webmail Developer   [http://roundcube.net]
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