Sugestion for a const implementation

[Andrei Alexandrescu (See Website For Email)]

Miles wrote:
> Andrei Alexandrescu (See Website For Email) wrote:
>> That's pretty limiting; you can't define something a la STL begin() that
>> returns different objects depending on the object's mutability.
> 
> This is almost prejudice against const. You broke my message in this
> point just to argue against it, without considering the explanation that
> follows.
> 
> If you think just a little about the solution, you will see that the
> solution cames immediately. iterator<> and const_iterator<> will became
> the exact same class, with no distinction between const and non-const.

I broke the message because it was long, having some content that I 
agree with (as in "true but uninteresting"). If you get to work out on 
an actual design for your idea, you will just see how it does not work.

>> Littering declarations is objective. In C++ const is never deduced, only
>> checked. The underlying vision is that there should be cases in which
>> constness is deduced such that programmers can benefit of it without
>> having to babysit the compiler.
> 
> I don't share your vision. Doesn't make any sense the compiler deduce const.

Well this is simply wrong, and fortunately there's no need for an 
explanation because there is plenty of previous work on qualifier 
inference (http://www.cs.umd.edu/~jfoster/papers/pldi99.pdf and 
Faehndrich follow-up work). Walter and I already discussed a number of 
workable instances of const deduction.


Andrei