How do you create a .di file for multiple .d files?

[Jesse Phillips]

Jonathan M Davis Wrote:

> It's what Walter suggested doing to have a single std.datetime to import but 
> have multiple modules for the actual implementation (he mentioned it in the 
> datetime review thread on the Phobos list). He said to look at druntime for 
> examples, but all of the .di files that I see there appear to have a single .d 
> file corresponding to them. If there is one with multiple .d files, I missed it.
> 
> - Jonathan M Davis

Ah, yes. I thought you had done some big work in D, so I thought it odd you would be confused on modules. I believe you were referring to this part from Walter:

> Remember, if a module's implementation code is large, it can be split
> into a .di/implementation pair, rather than into multiple modules.

And the later follow up.

> Jonathan M Davis wrote:
>
>>    Really, the ideal would be to have all of it in one module but have the code split up into several files. 
>> The closest way that I was aware to do that was to use a single module which publicly imported the 
>> others. I'll look at splitting it into an interface file and source file though.

> druntime does it for several modules, and can serve as an example.

I think I read into that differently. I was thinking he meant that by creating a D interface file you no longer have all the implementation making the file look big. I didn't understand the benefit, nor how it related to the problem.

On another note, why does druntime ship with .di files and .d files? Phobos is only .d