Hi all,
with the oncoming of JDK9 we are facing a problem with @Grab, which is
that there is no URLClassLoader to hook into anymore by default.
Actually that was never a guarantee, just worked in almost all of the
scenarios of interest.
@Grab(group='commons-lang', module='commons-lang', version='2.4')
import org.apache.commons.lang.WordUtils
println "Hello ${WordUtils.capitalize('world')}"
There are two basic flavors to @Grab, which is using it with a source
file and using it with a precompiled file. In both cases the @Grab would
download dependencies and try to give the executing environment those
dependencies.
In case of a source file, we hook into the compiler to do the downloads
as well as change the static constructor of the class. So we ensure we
can compile the file and since we have full control over the execution
environment in this case we can also ensure all the libraries are
available before the class is loaded by the JVM.
In the precompiled case, for example as a testcase, we do not have full
control over the environment and with JDK9 there might not be a single
URLClassloader we can use anymore. Furthermore here is a limitation of
@Grab, which is that the grabbed classes cannot be used in any of the
signatures of the class.
So now the question is what we want to do. The most simple version would
be to ditch the precompiled version. If we want to keep it like is, we
will have to add JDK9 specific code handling layers and modules.
What do you think?
bye Jochen
