Scoped Operator Overloading

[Morning Song]

On Sunday, 2 June 2013 at 05:27:08 UTC, Carl wrote:
> I am writing a class to act like a database or cache. I want to 
> enable looping with foreach, but I need two separate opApply 
> methods. One for the internal looping through raw data and a 
> second for looping through the cached data (strings for 
> example).
>
> Is there a way to scope the first opApply (looping through raw 
> data) to only be accessible inside the class? This would be 
> beneficial to prevent someone from accidentally looping through 
> raw data instead of their cached objects.

If the delegates to the opApply have different parameters (I.e.
it's actually a different data type getting passed to the foreach
loop), then method overloading will take care of it; just mark
one of them private.

If they both need to get sent the same kind of data, it's a hack,
but you could try encapsulating the data for the raw one inside a
private struct. Then, inside the foreach loop, you can "unpack"
the data from the struct before using it.
std.typecons.Typedef!(T) might also help--As I understand, it'll
make a type alias that's considered by the compiler to be a
separate data type.