Fully transitive const is not necessary

[Sean Kelly]

Janice Caron wrote:
> On 27/04/2008, Sean Kelly <sean at invisibleduck.org> wrote:
>> what do they achieve that could not have been
>> achieved via plain old const strings?
> 
> In a word: (OK - in three words): Copy On Write.
> 
> For example, one could write a function
> 
>     string escape(string s);
> 
> which escaped certain characters (by preceding them with '\' or
> whatever). Because s is an array of invariant chars, if nothing needs
> to be escaped, the function is able to return s.

So this is predicated on the idea that the optimal strategy is to assume 
that library functions will not actually need to make any changes the 
majority of the time, and that they do COW internally.  Fair enough.  I 
agree that this makes it a clear win for Phobos, which is designed 
around this assumption.


Sean