unsafe toString() behavior

[Chris Miller]

On Tue, 27 Jun 2006 00:44:05 -0400, BCS <BCS_member at pathlink.com> wrote:

> In article <op.tbr0mdsfpo9bzi at moe>, Chris Miller says...
>>
>> On Mon, 26 Jun 2006 19:18:15 -0400, lenfestey at geemail.com  =
>>
>> <lenfestey_member at pathlink.com> wrote:
>>
>>> import std.stdio;
>>> import std.string;
>>>
>>> void main() {
>>> char[] x =3D toString(0);
>>>
>>> // la de da...
>>> x[0] =3D 'a';
>>>
>>> // guess what i print
>>> writefln("x=3D%s", toString(0));
>>> }
>>>
>>> It is because toString(uint) sometimes returns an array slice.
>>>
>>> Aaron Lenfestey
>>
>> In D you have to practice COW (copy-on-write) unless you are certain you
>> are the only one using the memory.
>
> IM(h)O toString should *always* return a copy.
>

Nah, I disagree. Take MemoryStream for example, what if it has 2MB, you  
want that copied every toString. This COW is just a different method than  
what's common in other languages, and yields such a great performance  
boost. If you want a copy, copy it. But if all you want to do is read the  
value, what is the point in copying.

Plus, where does this copying stop? Should every function returning an  
array, or even a reference, make sure the caller gets a copy he can modify?

However, I think I would be in favor of some type of immutability,  
provided it isn't so wordy and troublesome as C/C++'s.