Project Elvis

[Steven Schveighoffer]

On 10/29/17 10:35 AM, Ola Fosheim Grøstad wrote:
> On Sunday, 29 October 2017 at 14:27:34 UTC, Ola Fosheim Grøstad wrote:
>> On Sunday, 29 October 2017 at 11:23:19 UTC, Steven Schveighoffer wrote:
>>>> So, what will the member function be called? «opElvis»? No…
>>>
>>> opCast for bool.
>>
>> That means you cannot create your own type-safe filtering mechanism, 
>> but will be forced to provide opCast for bool.
> 
> That breaks down if you want do filter out invalid values where zero is 
> a valid value. For instance if you have an integer type that tracks 
> overflow:
> 
> calc(maybe_overflow_integer :? 0)
> 
> So casting to bool is a poor choice for the typical use context.

I would have expected Nullable!int to fit the bill, but unfortunately, 
opCast(bool) doesn't work on a null Nullable.

But certainly you can construct a type that does work.

-Steve