Regarding hex strings

[Don Clugston]

On 18/10/12 17:43, foobar wrote:
> On Thursday, 18 October 2012 at 14:29:57 UTC, Don Clugston wrote:
>> On 18/10/12 10:58, foobar wrote:
>>> On Thursday, 18 October 2012 at 02:47:42 UTC, H. S. Teoh wrote:
>>>> On Thu, Oct 18, 2012 at 02:45:10AM +0200, bearophile wrote:
>>>> [...]
>>>>> hex strings are useful, but I think they were invented in D1 when
>>>>> strings were convertible to char[]. But today they are an array of
>>>>> immutable UFT-8, so I think this default type is not so useful:
>>>>>
>>>>> void main() {
>>>>>    string data1 = x"A1 B2 C3 D4"; // OK
>>>>>    immutable(ubyte)[] data2 = x"A1 B2 C3 D4"; // error
>>>>> }
>>>>>
>>>>>
>>>>> test.d(3): Error: cannot implicitly convert expression
>>>>> ("\xa1\xb2\xc3\xd4") of type string to ubyte[]
>>>> [...]
>>>>
>>>> Yeah I think hex strings would be better as ubyte[] by default.
>>>>
>>>> More generally, though, I think *both* of the above lines should be
>>>> equally accepted.  If you write x"A1 B2 C3" in the context of
>>>> initializing a string, then the compiler should infer the type of the
>>>> literal as string, and if the same literal occurs in the context of,
>>>> say, passing a ubyte[], then its type should be inferred as ubyte[],
>>>> NOT
>>>> string.
>>>>
>>>>
>>>> T
>>>
>>> IMO, this is a redundant feature that complicates the language for no
>>> benefit and should be deprecated.
>>> strings already have an escape sequence for specifying code-points "\u"
>>> and for ubyte arrays you can simply use:
>>> immutable(ubyte)[] data2 = [0xA1 0xB2 0xC3 0xD4];
>>>
>>> So basically this feature gains us nothing.
>>
>> That is not the same. Array literals are not the same as string
>> literals, they have an implicit .dup.
>> See my recent thread on this issue (which unfortunately seems have to
>> died without a resolution, people got hung up about trailing null
>> characters without apparently noticing the more important issue of the
>> dup).
>
> I don't see how that detail is relevant to this discussion as I was not
> arguing against string literals or array literals in general.
>
> We can still have both (assuming the code points are valid...):
> string foo = "\ua1\ub2\uc3"; // no .dup

That doesn't compile.
Error: escape hex sequence has 2 hex digits instead of 4