I disagree with you.
When writing a library I think it is much cleaner to explicitly show what you are using.
If its your 13’th lib, you may be right. Otherwise you will have a hard time finding and adding #include-statements for all of the functions provided by the core.
So I’ll try again :
You could #include <HardwareSerial.h>
Don’t do this unless you have a good knowledge about the inner workings of the Core. All the core functions are available to your library when “WProgram.h” is included.
It also takes less time to compile.
No to this one.
All the files that belong to the core are compiled and linked with the code that gets uploaded, no matter if you use any of the functions the core provides.
But this is only academic : compile times don’t really matter when writing software with the IDE.
After this little dog-member shootout is over, did this get you anywhere?
Otherwise you should probably post the library-code.