Scope of D packages

[Enamex via Digitalmars-d-learn]

On Saturday, 19 December 2015 at 00:46:12 UTC, cym13 wrote:
> To be exact it doesn't need the sources, it needs the function 
> signatures and type definitions so the equivalent of C header 
> files. If you don't want to share the full sources with your 
> library you can generate those header files automatically using 
> the -H flag in dmd. It will produce a "D interface" file with a 
> "di" extension.

How does this interact with templates and introspective code?