Head Const

[Ola Fosheim Grøstad via Digitalmars-d]

On Monday, 15 February 2016 at 22:48:16 UTC, Walter Bright wrote:
> rears its head again :-)
>
> Head Const is what C++ has for const, i.e. it is not 
> transitive, applies to one level only. D has transitive const.
>
> What head const will do for us:
>
> 1. make it easy to interface to C++ code that uses const, as 
> currently it is not very practical to do so, you have to resort 
> to pragma(mangle)
>
> 2. supports single assignment style of programming, even if the 
> data is otherwise mutable
>
> The downside is, of course, language complexity.

Maybe you can get away with adding "mutable", which is needed for 
intrusive ref counting as well:

C++:
Type * const ptr;

struct ConstType {
mutable int rc;
}


D:
const mutable(Type)* ptr;

struct ConstType {
mutable(int) rc;
}