type of concatenated arrays

[BCS]

Janice Caron wrote:
> On 11/7/07, Steven Schveighoffer <schveiguy at yahoo.com> wrote:
> 
> 
>>Now, a2 is declared as a const(char)[] array, but I think it should be just
>>a char[] array.  Why?  because the concat operator should have made a copy
>>of the array with length +1 and added the \n character.  If this is the
>>case, I should be able to do whatever I want with the copy.  Why does it
>>have to be const?
> 
> 
> Because of copy-on-write.
> 
> If b is the empty string, then (a ~ b) will evaluate to a. No copy need be made.

from the spec:

"Concatenation always creates a copy of its operands, even if one of the 
operands is a 0 length array"

http://www.digitalmars.com/d/arrays.html
grep for "~" and look down about 8 lines