Is there a more elegant way to do this?

[Nicholas Wilson via Digitalmars-d-learn]

On Sunday, 12 March 2017 at 05:13:41 UTC, bauss wrote:
> I was wondering if there's a more elegant way to do something 
> like this?
>
> template BitSize(T) {
> 	enum BitSize = T.sizeof * 8;
> }
>
> struct Data(ParentType,ChildType) {
> 	@property {
> 		ChildType low() { return cast(ChildType)value; }
> 		void low(ChildType lowValue) {
> 			value = ((high << (BitSize!ParentType / 2)) | lowValue);
> 		}
> 		
> 		ChildType high() { return cast(ChildType)(value >> 
> (BitSize!ParentType / 2)); }
> 		void high(ChildType highValue) {
> 			value = ((highValue << 16 | low));
> 		}
> 	}
> 	
> 	ParentType value;
> 	
> 	alias value this;
> }
>
> Example usage:
> void main() {
> 	Data!(uint,ushort) data;
> 	data = 14065735;
> 	
> 	writefln("low: %s high: %s", data.low, data.high);
> 	
> 	data.low = 41031 ;
> 	data.high = 214;
> 	
> 	writefln("value: %s", data.value);
> }
>
> Basically to explain what it is: You give it a parent-type and 
> a corresponding child-type.
>
> Ex. if the parent-type is uint, the child-type would be ushort.
>     if the parent-type is long, the child-type would be int.
>     etc.
>
> What it allows you to is to either manipulate the data as the 
> parent-type or as two values of the child type.
>
> I was just wondering if there's a more elegant or performant 
> way to do this, perhaps something in Phobos exist already?

template HalfSize(T)
{
     static if (T==long)
         alias HalfSize == int;
     // repeat for all combos
}

struct Data(T)
{
     union
     {
          T value;
          struct
          {
               version(LittleEndian)
               {
               HalfSize!T low;
               HalfSize!T high;
               }
               version(BigEndian)
               {
               HalfSize!T low;
               HalfSize!T high;
               }
          }
     }
     alias value this;
}