> On Jul 12, 2021, at 11:00 AM, Larry Garfield <la...@garfieldtech.com> wrote:
> x
> On Mon, Jul 12, 2021, at 9:54 AM, Max Semenik wrote:
>
>> I was thinking of something akin to many compiled languages' approach of
>> "consider this expression is now of that type, and throw an exception if
>> it's not". An example of this approach from Benjamin's proposal of old^
>>
>> $service = (EmailService) $diContainer->get('email.service');
>>
>> Instead of
>>
>> /** @var EmailService $service */
>> $service = $diContainer->get('email.service');
>> if (!$service instanceof EmailService) {
>> throw new TypeError('Expected instance of EmailService, ...');
>> }
>
> Hm, that's a different creature. I... would be probably OK with something in
> that direction, though I wouldn't work on it myself. I think what you're
> describing here is more of a type assertion. "Assert that this variable is
> of type X, otherwise bail." So, some kind of non-disableable (or maybe
> disableable?) shorthand for `assert($foo instanceof Bar)`.
Regarding prior art on type assertion, the syntax Go uses is `value.(type)` so
using a similar approach in PHP might look like this (I'm spitballing by using
the double colon as a sigil but it could anything that doesn't conflict with
existing usage, whatever those options are):
$service = $diContainer->get('email.service')::(EmailService);
Additionally in Go a type assertion can return a second value which is boolean
telling if the type assertion succeeded. Not having this would effectively
moot the benefit to a type assertion if you had to wrap with try{}catch{} in
case it failed.
$service, $okay = $diContainer->get('email.service')::(EmailService);
if (!$ok) {
echo 'Not an EmailService.';
}
#fwiw
-Mike
