Endianness - How to test code for portability

[Preetpal]

On Friday, 12 March 2021 at 10:26:55 UTC, Dennis wrote:
> ```
> version(BigEndian) {
>     private enum bigEndian = true;
> } else {
>     private enum bigEndian = false;
> }
>
> int parse(in ubyte[] data) {
>     if (__ctfe || bigEndian) {
>         // Portable code
>     } else {
>         // Little-endian optimized code
>     }
> }
> ```
>
> Then you can test both at runtime and compile time:
> ```
> unittest {
>     ubyte[] testData = [...];
>     assert(parse(testData) == 3);
>     static assert(parse(testData) == 3);
> }
> ```
>
> So no, I don't have a big-endian computer I can test it on, but 
> I do test with CTFE, so I'm pretty sure I'm not relying on a 
> specific byte order.

I never even thought of using CTFE for this purpose. Using CTFE 
to test cases you cannot simulate using runtime testing is a 
really great idea.