TypeFunction example creatiing a conversion matrix

[Steven Schveighoffer]

On 10/1/20 2:32 PM, Andrei Alexandrescu wrote:
> On 10/1/20 2:26 PM, Steven Schveighoffer wrote:
>> On 10/1/20 2:10 PM, Andrei Alexandrescu wrote:
>>> On 10/1/20 1:55 PM, Stefan Koch wrote:
>>>> Please show me in the code where is(T : U) is used.
>>>> I don't find it in std variant.
>>>
>>> It's in the use of ImplicitConversionTargets in std.traits.
>>
>> The only use of is(T:U) in that trait is:
>>
>> is(T : typeof(null))
> 
> Of course. That's the point - the template is not using "is", because it 
> can't: it only has one type available. It "implements" a subset of it. 
> See what I'm saying? ImplicitConversionTargets helps Variant implement a 
> kinda sorta "is" at runtime.
> 

Yes, I see. This subthread confused me...

-Steve