preparing for const, final, and invariant

[Reiner Pope]

Walter Bright wrote:
> Regan Heath wrote:
>> Why not make this implicit 'in' parameter 'scope const final' avoiding 
>> the need to explicity say 'in' everywhere?
> 
> It's a good idea, but then there needs to be some way to pass a mutable 
> reference. Such as:
> 
> class C { int x; }
> void foo(C c)
> {
>     c.x = 3;
> }
> 
> That doesn't work if 'const' is the default. Using out or inout doesn't 
> work either, as those have slightly different semantics (an extra level 
> of indirection).

At the risk of aggravating more people by adding Yet Another Keyword, 
how about 'const scope final' by default, with some negative keywords to 
undo it.

Like, say, unconst and unscope:

void foo(unconst C c)
{
     c.x = 3;
}

or why not use the ! operator, which already means 'not':

void foo(!const C c)
{
     c.x = 3;
}

Cheers,

Reiner