Re: [RFC] Patch for Union and Intersection Types
| From: | Levi Morrison | Date: | Tue, 26 Apr 2016 17:26:05 +0000 |
| Subject: | Re: [RFC] Patch for Union and Intersection Types | ||
| References: | 1 2 3 4 5 6 7 8 | Groups: | php.internals |
| Request: | Send a blank email to internals+get-92807@lists.php.net to get a copy of this message | ||
On Tue, Apr 26, 2016 at 11:20 AM, Levi Morrison <morrison.levi@gmail.com> wrote:
> On Tue, Apr 26, 2016 at 11:00 AM, Niklas Keller <me@kelunik.com> wrote:
>> 2016-04-26 16:58 GMT+02:00 Bob Weinand <bobwei9@hotmail.com>:
>>>
>>> Yeah, I'd like to not allow ?Foo in any case if union types pass.
>>
>>
>> What's the reason for that? To me, null is neither a type nor should it be.
>
> On the contrary, our manual says:
>
>> NULL is the only possible value of type null.
>
> And internally it is also a distinct type.
>
> It's been this way for a long time; we just haven't permitted
>
null
> as a type declaration because until now it has been useless.
To further expand on why it was previously useless:
function foo(Null $a) {
return $a;
}
There is only one possibility for this parameter, which is the value
NULL. There is hardly any value to it when you can just write this
instead:
function foo() {
return NULL;
}
In words: if the only possible value for a parameter is null then it's
not really a parameter; it's just a constant value and doesn't need to
be parameterized.