Convert this C macro kroundup32 to D mixin?

[biocyberman via Digitalmars-d-learn]

On Saturday, 8 April 2017 at 21:34:30 UTC, Ali Çehreli wrote:
> You can mixin declarations with a template but I don't see how 
> it can help here. A string mixin would work but it's really 
> ugly at the use site:
>
> string roundUp(alias x)()
> if (is (typeof(x) == uint)) {
>
>     import std.string : format;
>     return format(q{
>         --%1$s;
>         %1$s |= %1$s >>  1;
>         %1$s |= %1$s >>  2;
>         %1$s |= %1$s >>  4;
>         %1$s |= %1$s >>  8;
>         %1$s |= %1$s >> 16;
>         ++%1$s;
>         }, x.stringof);
> }
>
> void main() {
>     uint i = 42;
>     mixin (roundUp!i);    // <-- Ugly
>
>     assert(i == 64);
> }
>
> Compare that to the following natural syntax that a function 
> provides:
>
> void roundUp(ref uint x) {
>     // ...
> }
>
> void main() {
>     uint i = 42;
>     i.roundUp();    // <-- Natural
> }
>
> Ali

You made the point, it looks really ugly :). However, sometimes 
if this ugliness offer better performance, I would - in a 
desperate mood - use it. That's only 'if'. I put two other 
variant to a test, and this ugly version does worst as well. You 
can check out here: 
https://gist.github.com/biocyberman/0ad27721780e66546cbb6a39c0770d99

Maybe it is because string formating cost. Moving the import 
statement out of the function does not speed things up.