string is rarely useful as a function argument

[Don]

On 31.12.2011 17:13, Timon Gehr wrote:
> On 12/31/2011 01:15 PM, Don wrote:
>> On 31.12.2011 01:56, Timon Gehr wrote:
>>> On 12/31/2011 01:12 AM, Andrei Alexandrescu wrote:
>>>> On 12/30/11 6:07 PM, Timon Gehr wrote:
>>>>> alias std.string.representation raw;
>>>>
>>>> I meant your implementation is incomplete.
>>>
>>> It was more a sketch than an implementation. It is not even type safe
>>> :o).
>>>
>>>>
>>>> But the main point is that presence of representation/raw is not the
>>>> issue.
>>>> The availability of good-for-nothing .length and operator[] are
>>>> the issue. Putting in place the convention of using .raw is hardly
>>>> useful within the context.
>>>>
>>>
>>> D strings are arrays. An array without .length and operator[] is close
>>> to being good for nothing. The language specification is quite clear
>>> about the fact that e.g. char is not a character but an utf-8 code unit.
>>> Therefore char[] is an array of code units.
>>
>> No, it isn't. That's the problem. char[] is not an array of char.
>> It has an additional invariant: it is a UTF8 string. If you randomly
>> change elements, the invariant is violated.
>
> char[] is an array of char and the additional invariant is not enforced
> by the language.

No, it isn't an ordinary array. For example with concatenation.  char[] 
~ int will never create an invalid string. You can end up with multiple 
chars being appended, even from a single append. foreach is different, 
too. They are a bit magical.
There's quite a lot of code in the compiler to make sure that strings 
remain valid.

The additional invariant is not enforced in the case of slicing; that's 
the point.