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Date: Thu, 14 Jun 2018 17:57:30 +0200 (CEST)
Subject: Re: [PHP-DEV] Strict switch statements
From: mails@thomasbley.de ("Thomas Bley")

Nikita Popov wrote on 14.06.2018 10:35:

> On Thu, Jun 14, 2018 at 6:53 AM, Sara Golemon <pollita@php.net> wrote:
> 
>> Just for casual discussion at this point:
>> https://github.com/php/php-src/pull/3297
>>
>> switch ($a) {
>>   case FOO:
>>       // Works exactly as current behavior.
>>       break;
>>   case == FOO:
>>      // Nearly identical, though not using the ZEND_CASE optimization.
>>      // Can probably make this equivalent to `case FOO`, but it felt
>> like an interesting direction.
>>      break;
>>   case === FOO:
>>      // Only triggers if `$a === FOO`, no type juggling
>>      break;
>> }
>>
>> Love it? Hate it? See obvious flaws?  The implementation is just a
>> rushed proof of concept, not something I've labored over, it may well
>> have bugs.  Certainly wouldn't target anything earlier than 7.4, if at
>> all.
>>
> 
> I like the general idea here (switch with strict type comparison), but not
> super fond of the particular syntax and implementation.
> 
> I think if people want to use strict matching, they'll quite likely want to
> have it on all cases. Something like "strict switch ($expr) {}" or "switch
> strict ($expr) {}" or "switch (strict $expr) {}" or "switch ($expr) strict
> {}" or "switch ($expr) { strict; }" or whatever would be preferable in that
> case.
> 
> Additionally, switch has the issue of fall-through behavior, which is
> somewhat unexpected and error prone to many people. It might make sense to
> introduce an entirely new "match" statement that conforms a bit more with
> how switch-like strictures are implemented nowadays. That is, something like
> 
> match ($expr) {
>    "foo" => {...},
>    "bar" | "baz" => {...},
> }
> 
> or similar. This might need some more design work to ensure forward
> compatibility with potential future algebraic datatypes etc.
> 
> Nikita
> 

for simplicity I would use an extra parameter to have a strict comparison (similar to the extra parameter in in_array()):

switch ($a, true) { // strict comparison
switch ($a) { // loose comparison

Regards
Thomas