Extended Type Design.

[kris]

Andrei Alexandrescu (See Website For Email) wrote:
> Bill Baxter wrote:
> 
>> Andrei Alexandrescu (See Website For Email) wrote:
>>
>>> Benji Smith wrote:
>>
>>
>>>> I reiterate: "const" and "readonly" are the way to go. (Methods 
>>>> which promise not to modify the values of their parameters should 
>>>> use "readonly" rather than "const" in their method signatures.)
>>>
>>>
>>> This makes const gratuitously incompatible to C++'s const, and 
>>> (worse) also adds a keyword that's its equivalent. I don't think this 
>>> can fly.
>>
>>
>> What about 'immutable' for 'really can't change'/'superconst', and 
>> const can stay as is?
> 
> 
> I like it, and suggested it at a point. Walter said that it's bad 
> marketing to define keywords in terms of a negative.

So, "invariant" is already a keyword ... what about that?

"Invariant" is currently used to stipulate a condition that must remain 
constant (or true) for the extent of the enclosing/relevant scope. Right 
now, it is used within a class only, but the semantics could presumably 
extend elsewhere too:

invariant int * p = &x;

void myFunc (invariant char[] arg) {}

in both these cases, the "invariance" should remain for the extent of 
the relevant scope?