A case for -H header files, avoid repeating expensive compile-time calculations

[rikki cattermole via Digitalmars-d]

On 28/08/2016 6:34 AM, cy wrote:
> I made a module that looped for a while in compile time (since you can't
> sleep during compile time), to see if I could pre-compile the module,
> and thus save time compiling the main application. It didn't work at
> first, because any file that depended on the module would import it, and
> importing it would execute the compile time code again, thus taking a
> long time to compile... twice.
>
> But then I remembered about the rarely used -H option for dmd. -H
> outputs a stripped down version of the source file being compiled, with
> all the function definitions replaced with declarations. So if your
> expensive to compile code is encapsulated within a function... it
> doesn't appear in the -H output.
>
> So uh... git://critter.cloudns.org/test-dlang-encapsulation I guess. It
> might be a neat trick to speed up compilation, if you have a lot of
> complicated code that can be hidden behind a simple interface.

Sounds like a use case for creating a source file in a pregeneration step.