Integer precision of function return types

[Salih Dincer]

On Thursday, 26 September 2024 at 06:53:12 UTC, Per Nordlöw wrote:
> Should a function like
>
> ```d
> uint parseHex(in char ch) pure nothrow @safe @nogc {
> 	switch (ch) {
> 	case '0': .. case '9':
> 		return ch - '0';
> 	case 'a': .. case 'f':
> 		return 10 + ch - 'a';
> 	case 'A': .. case 'F':
> 		return 10 + ch - 'A';
> 	default:
> 		assert(0, "Non-hexadecimal character");
> 	}
> }
> ```
>
> instead return an ubyte?

When I use standard library facilities, I try to use ubyte; for 
example:

(See "toggle comment" in the section...)

```d
void parseFromHexString(R)(out R hex, const(char)[] str)
{
   import std.algorithm : map, copy;
   import std.conv      : to;
   import std.range     : front, chunks;

   alias T = typeof(hex.front);
   str.chunks(T.sizeof * 2)
      .map!(bin => bin
      .to!T(16))
      .copy(hex[]);
}

import std.stdio;
void main()
{
   enum hex = "48656C6C6F2044202620576F726C6421";
   enum size = hex.length / 2;

   auto sample = imported!"std.conv".hexString!hex;
   sample.writeln; // Hello D & World!

   enum hexStr = x"48656C6C6F2044202620576F726C6421";
   hexStr.writeln; // Hello D & World!
   assert(is(typeof(hexStr) == string));

   immutable int[] intStr = x"48656C6C6F2044202620576F726C6421";
   intStr.writeln; // [1214606444, 1864385568, 639653743, 
1919706145]


   int[size] buf;
   buf.parseFromHexString(hex);
   buf.writeln;

   //char[size] buff; /*
   ubyte[size] buff;/* please toggle comment with above */
   buff.parseFromHexString("BADEDE");
   buff.writeln;
```

But when I try to do something with my own functions, I have 
control and I do what I want. You can also use char below, ubyte 
is not a problem either:

```d
auto toHexDigit(char value)
{
   if(value > 9) value += 7;
   return '0' + value;
}

auto toHexString(R)(R str)
{
   string result;

   char a, b;
   foreach(char c; str)
   {
     a = c / 16; b = c % 16;
     result ~= a.toHexDigit;
     result ~= b.toHexDigit;
   }
   return result;
}

void main() {  assert(sample.toHexString == hex); }
```

SDB at 79