Yes, if you have "class Box<T extends Boxable>" and T is used for two
things, then "they must be of the same type, but they can be any same type
and that type must at least be Boxable". It means that Box can use a T as a
Boxable (call Boxable methods on it, etc).
On Thu, Apr 21, 2016 at 1:12 AM, Larry Garfield <la...@garfieldtech.com>
wrote:
> On 4/20/16 10:01 AM, Rowan Collins wrote:
>
>> guilhermebla...@gmail.com wrote on 20/04/2016 03:54:
>>
>>> 1- Even though mentioned, I'd still use "extends" or "implements" instead
>>> of "is" (which would be a new pseudo-reserved keyword) to enforce data
>>> type
>>> consistency and prevent developers to potentially referring to one thing
>>> while consider another.
>>>
>>
>> Perhaps "instanceof" would make more sense here? "class FileProcessor<T
>> extends FileHandle>" seems to exclude instantiating
>> FileProcessor<FileHandle>, because "FileHandle extends FileHandle" doesn't
>> make any sense.
>>
>> You could read "class Box<T instanceof Boxable>" as an assertion that the
>> class passes the constraint, as in "public function __construct(T $t) {
>> assert($t instanceof Boxable); }"
>>
>> Regards,
>>
>
> I'm not an expert in generics by any means, but how is that different than
> just
>
> public function __construct(Boxable $t) {}
>
> I thought the point of generics was for cases like "these two variables
> must be the same type, but they can be any same type."
>
> --
> --Larry Garfield
>
>
>
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