Extended Type Design.

[Andrei Alexandrescu (See Website For Email)]

eao197 wrote:
> On Fri, 16 Mar 2007 00:16:48 +0300, Andrei Alexandrescu (See Website For 
> Email) <SeeWebsiteForEmail at erdani.org> wrote:
> 
>> a) final - a simple storage class controlling the immutability of the 
>> bits allocated for the symbol per se;
>>
>> b) const - type qualifier meaning an immutable view of an otherwise 
>> modifiable data. const does not control the bits of the object, only 
>> the storage addressed indirectly by it (transitively);
>>
>> c) "superconst" - denoted as "const!" or "super const": type qualifier 
>> meaning that the data is genuinely unmodifiable.
> 
> Great!
> 
> What about the influence of this storage classes on class method's 
> signatures? Is this will be in D:
> 
> class Data { ... }
> 
> class Container {
>   // non-const access to data.
>   Data data() { ... }
>   // const access to data.
>   const Data data() const { ... }
> }
> 
> void useContainer( const Container c ) {
>   auto d = c.data(); // the type of d is 'const Data'.
>   ...
> }
> 
> ?

Yes, that's part of the plan. Moreover, you'll likely have the ability 
to define const-transporting methods (methods that look identical but 
only need to pass the const of the object out to the return value) only 
once. This has been a source of annoyance in certain C++ idioms.


Andrei