Extend the call site default argument expansion mechanism?

[Yuxuan Shui]

On Tuesday, 15 May 2018 at 13:59:37 UTC, jmh530 wrote:
> On Tuesday, 15 May 2018 at 13:16:21 UTC, Steven Schveighoffer 
> wrote:
>> [snip]
>>
>> Hm... neat idea. Somehow, opDispatch can probably be used to 
>> make this work even more generically (untested):
>>
>> struct WithAlloc(alias alloc)
>> {
>>    auto opDispatch(string s, Args...)(auto ref Args args) if 
>> (__traits(compiles, mixin(s ~ "(args, alloc)")))
>>    {
>>       mixin("return " ~ s ~ "(args, alloc);");
>>    }
>> }
>>
>> -Steve
>
> Example:
> https://run.dlang.io/is/RV2xIH

Sadly with(WithAlloc!alloc) doesn't work. (If you have to use 
withAlloc.func everywhere, it kind of destroy the point, doesn't 
it?)