Re: const, auto and struct/class methods

[Andrea Fontana]

On Monday, 25 November 2013 at 09:05:39 UTC, Joseph Rushton 
Wakeling wrote:
Hello all,

If I mark a struct or class method as const, this is assumed to 
apply to the entire method, i.e. that nothing in it will modify 
any internal data of the struct/class.

    struct Foo
    {
        const auto bar()
        {
            // I can't modify any of the
            // internal data of Foo here
        }
    }

Suppose instead that I want a method that _may_ modify internal 
data, but will return an entity that is itself const.  Is there 
any way to do this while having the return type being declared 
via auto?

i.e. what I want to be able to do is something like,

     struct Foo
     {
          const(auto) bar()
          {
              // modifies internal data of Foo
              // but returns a const type
          }
     }

(Note that const(auto) of course is not valid D, I use it for 
illustrative purposes:-)

Is something like this possible, and if so, what's the correct 
notation?

Thanks and best wishes,

    -- Joe

auto bar() { return cast(const int) 10; }

writeln(typeid(bar()));

?