On 28/06/2021 09:49, Christian Beikov wrote:
Hello experts,
I am in the process of modularizing one of my projects and hit some
rather annoying limitations that requires me to change parts of my
build and dependencies due to the way the Java module system works.
I usually have modules like x-api, x-impl and x-testsuite where I have
a compile time dependency from x-impl to x-api. In x-testsuite I only
code against x-api, so I define a Maven runtime dependency on x-impl
in order for my CDI container to pick up the implementations. The
annoying part is that with modularization I now need to declare my
dependency in x-testsuite on x-impl as compile time dependency,
because otherwise I can't list the module in the module-info. If I
don't list the module, then it is not "visible" to the CDI container,
which I guess is on purpose, even though it probably ends up in the
module path.
Is that by design that classes are not visible if no module depends on
a module like x-impl in such a scenario, or is that maybe something
that could work and should be improved in the CDI implementation? I
was thinking that if "requires runtime ..." were allowed without
checking that the module is available during compilation, this would
work fine. Did this idea come up before already?
The module system supports services. x-api uses a service, x-impl
provides an implementation of the service. If x-api is resolved then all
observable modules that provide an implementation of the services used
by x-api will be resolved too. In this scenario, x-impl requires x-api,
x-api does not require x-impl. You used the phrase "compile time
dependency" but it's more than that, it's all phases as there will be
references in x-impl to x-api's exported API.
I don't know if you control the CDI implementation or not but if you
aren't using services then you'll need to help the module system with
"--add-modules x-impl". This is because no other module requires x-impl
and it's not providing an implementation of a service. It may be
observable but it's the same directory as 99,999 other modules that you
don't care about.
-Alan
