The baby and the bathwater

[Peter Levart]

On 03/26/18 20:08, mark.reinhold at oracle.com wrote:
> Stephen closes with a specific suggestion:
>
>    "There needs to be a way for a library author to insist that the
>     modular jar file they are producing can only be run on the module-path
>     (with any attempt to use it on the class-path preventing application
>     startup).  This would eliminate the need for testing both class-path
>     and module-path."

That's easy to enforce in runtime. Just take a "victim" class from your 
library that is most often needed when your library is being used (or 
take a couple of them) and add a class initialization block like the 
following to them:

public class Whatever {

     static {
         if (Whatever.class.getModule().getName() == null) {
             throw new Error("Can only use this library as a module");
         }
     }


Regards, Peter