How to instantiate a template struct with a template constructor without relying on auto deduction?

[ParticlePeter]

On Wednesday, 21 February 2018 at 14:29:31 UTC, Simen Kjærås 
wrote:
> On Wednesday, 21 February 2018 at 14:11:10 UTC, ParticlePeter 
> wrote:
>> struct Foo(T) {
>>   T bar;
>>   this(S)(S s) {
>>     bar = convert(s);
>>   }
>> }
>>
>> auto foo = Foo!int(some_float);
>>
>>
>> this works because S is deduced as typeof(some_float), but how 
>> would I instantiate the struct without relying on auto 
>> deduction?
>>
>> Suppose we would have this kind of constructor where auto 
>> deduction is not possible:
>>
>>   this(int n)(float f) {
>>     static foreach( i; 0..n) { do_some_ctfe_magic;}
>>   }
>>
>> How to instantiate Foo then?
>
> No can do. The solution is to use a factory function:

Feared the same, thanks.

> struct Foo(T) {
>     static Foo create(int n)(float f) {
>         Foo result;
>         static foreach( i; 0..n) { do_some_ctfe_magic;}
>         return result;
>     }
> }
>
> --
>   Simen

I will consider this, actually I use something quite close, but 
my create is not static and does not return anything. It simply 
initializes the struct after it has been constructed with the 
default ctor. The templated user ctor would have been nice, 
though.