template? mixin? template mixins? for modifying a struct setup

[user1234]

On Thursday, 19 May 2022 at 10:15:32 UTC, Chris Katko wrote:
> given
> ```D
> struct COLOR
> {
> float r, g, b, a; // a is alpha (opposite of transparency)
> }
>
> auto red   = COLOR(1,0,0,1);
> auto green = COLOR(0,1,0,1);
> auto blue  = COLOR(0,0,1,1);
> auto white = COLOR(1,1,1,1);
> //etc
> ```
>
> is there a way to do:
> ```D
> auto myColor = GREY!(0.5);
> // where GREY!(0.5) becomes COLOR(0.5, 0.5, 0.5, 1.0);
> ```

average is a bad way to grayscale FYI ;)