On 03/28/2018 11:18 AM, Stephen Colebourne wrote:
On 28 March 2018 at 08:28, Peter Levart <peter.lev...@gmail.com> wrote: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"); } }Agreed that this has always been possible, but it is code not metadata. Really, it should be a startup JPMS error if the module isn't running in the expected mode. That way tools like Maven and Gradle can also take decisions based on the metadata. Stephen
Hm, that would be hard to enforce, since what you're asking is for JPMS to issue an error when the library in question is not part of its search scope. Class-Path class loader could do that though (by searching for pa particular "sign" in the jars on the class path even before the JVM transfers control to MainClass.main()). But modulepath and classpath are not the only ways a particular jar can be deployed. It can be part of a .war or .ear. It can be deployed into a system that manages its own class loader(s), etc. All those mechanisms would have to agree on a "standard" way of specifying such metadata.
Regards, Peter
