how to implement a function in a different D source file

[Mike Parker]

On Tuesday, 26 November 2019 at 03:55:24 UTC, mipri wrote:
> On Tuesday, 26 November 2019 at 03:06:52 UTC, Omar wrote:
>> the page here https://dlang.org/spec/function.html
>> suggests you can implement a function in a different file
> ...
>> mentioned the endeavour of no-bodied-functions as a way of 
>> presenting a black-box type of interface.
>
> oh, that's what you were asking.
>
> Consider:
>
>   $ cat interface/references.d
>   module references;
>
>   string greeting();
>
>   $ cat implementation/references.d
>   module references;
>
>   string greeting() {
>       return "Hello, Dave";
>   }
>
>   $ cat main.d
>   import references;
>
>   void main() {
>       import std.stdio: writeln;
>       writeln(greeting);
>   }
>
> And trying to build it:
>
>   $ dmd -c implementation/references.d
>   $ dmd -Iinterface -c main.d
>   $ dmd main.o references.o
>   $ ./main
>   Hello, Dave

The idiomatic way to do that is to put the interface in a "D 
interface" file (.di) and the implementation in a .d file:

foo/bar.di
foo/bar.d

Then, when importing foo.bar, the compiler will pick up the .di 
file automatically.

And you can actually have the compiler generate the interface 
file for you from a source file with the -H option.