Creating ranges over mutable, const, or immutable data structures.

[Ali Çehreli via Digitalmars-d-learn]

On 05/24/2014 11:01 AM, Ali Çehreli wrote:
> On 05/24/2014 10:02 AM, w0rp wrote:
>
>  > I have been writing my own hashmap which can provide forward ranges
>  > usable in @safe pure nothrow functions, because it's going to be useful
>  > for creating graph data structures with the same. I came to writing my
>  > ranges and I figured out how to do everything right for just mutable
>  > hashmaps, but I have no idea how to manage the tail-const nature of
>  > ranges in a variety of combinations. I figured out that I need to
>  > satisfy the following constraints.
>  >
>  > Create a mutable KeyRange over a map which forwards on the right
>  > constness for the key type, so the following must be true.
>  >
>  > HashMap!(K, V).keys.front -> K
>  > const(HashMap!(K, V)).keys.front -> const(K)
>  > immutable(HashMap!(K, V)).keys.front -> immutable(K)
>  >
>  > I have encounted some difficulty in trying to write a range which does
>  > this.
>
> How timely! :) Jonathan Crapuchettes talked about facing the same issue
> in his talk at DConf. Perhaps he will post his WrapMutability template
> here or you can wait for his talk on YouTube.
>
> Ali
>

That presentation is published. WrapMutability appears at 32:55:

   http://www.ustream.tv/recorded/47930242

Ali