You add all those things in a single .c or .cpp source, without manual authoring of .h files (this may require language changes, maybe in C30 and C++30 or somet

You add all those things in a single .c or .cpp source, without manual authoring of .h files (this may require language changes, maybe in C30 and C++30 or something) Then whatever is relevant to the public interface gets generated by the compiler and put in a .h file. This file is not put in the same directory of the .c file to not encourage people to put the .h file in version control.