foreach on const(V[K])

[Dan]

On Tuesday, 27 November 2012 at 16:08:54 UTC, Andrei Alexandrescu 
wrote:
> As far as I understand you reveal it's impossible to iterate a 
> const(V[K]), which is an implementation bug. Please file it 
> with bugzilla.
>

Sure I will do that as I think it is impossible without a deep 
cast. But, I don't know that it is an implementation bug as much 
as a incorrect definition of the foreach per the langauge spec.

 From 'Foreach over Associative Arrays':

"The type of the variable must match the type of the array 
contents. If there are two variables declared, the first is said 
to be the index and the second is said to be the value. The index 
must be of the same type as the indexing type of the associative 
array. It cannot be ref, and it is set to be the index of the 
array element."

I do not understand why "it cannot be ref" and am suggesting that 
that should say and be implemented as rather: "it is naturally a 
ref, whether you include the ref keyword or not and in fact it is 
ref const(K). This way we could do:

foreach(k, ref v; aa) { }

when aa is a const(V[K]).