Multiple GrabResolvers with Grab don't seem to work, and GrabResolve can't be applied to imports

Disallowing duplicate annotations of the same type on one element was done under GROOVY-3852,
because when done, JVM starts having AnnotationFormatError issues at runtime when annotations
are accessed.

Some links about JVM not handling multiple annotations of the same type on same element:

1)http://stackoverflow.com/questions/1554112/multiple-annotations-of-the-same-type-on-one-element
2)http://www.docjar.com/html/api/sun/reflect/annotation/AnnotationParser.java.html

If multiple GrabResolver make sense, then what is needed is a new annotation @GrabResolvers
that can handle multiple GrabResolver entries.

Also both @Grab and @GrabResolver do not support being specified on import statements

@Grab/@GrabResolver targets :- CONSTRUCTOR, FIELD, LOCAL_VARIABLE, METHOD, PARAMETER, TYPE

So, as far as I understand, the whole behavior is as designed.

If I see http://java.sun.com/j2se/1.5.0/docs/api/java/lang/annotation/ElementType.html, I don't
even see any support in JDK for import statements being the target of annotations.

The only thing to do that is coming out of this JIRA is that there should be a @GrabResolvers and that
would be a new feature request, I guess.

I'm 99.8% sure you can use @Grab on an import

And maybe the GROOVY-3852 issue should only have prevented multiple @Retention(value=RUNTIME) annotations?

Could you file a JIRA issue for we make such an improvement with @GrabResolver?

I can only apologise Russel That hack makes me feel unclean when I think that it came from my hands

Yes, disallowing duplicate annotations only for Runtime retention policy seems correct to me.

I will raise a JIRA and fix that bit.

Tim,

Let me make you feel better: the hack has saved my talk for tomorrow at Groovy & Grails eXchange 2009. It may be a hack, but it works. You are officially a hero!

If you are playing with the snapshot versions of the groovy in your talk, then I have done a fix on the trunk
that allows multiple @GrabResolver (i.e, annotations not having retention policy as RUNTIME). I will be porting
this fix to 1.7.x and 1.6.x in a bit.

After the fix, point 1) from the JIRA is taken care of and the following works

@GrabResolver(name='jboss', root='http://repository.jboss.org/maven2')
@GrabResolver(name='codehaus.snapshot', root='http://snapshots.repository.codehaus.org')
def dummy() {}
@Grab(group='org.codehaus.gpars', module='gpars', version='0.9-beta-1')
import groovyx.gpars.actor.PooledActorGroup

println new PooledActorGroup()

In fact, in the very first example of JIRA, if I re-order annotations a bit, then the following works too:

@Grab(group='org.codehaus.gpars', module='gpars', version='0.9-beta-1')
@GrabResolver(name='jboss', root='http://repository.jboss.org/maven2')
@GrabResolver(name='codehaus.snapshot', root='http://snapshots.repository.codehaus.org')
import groovyx.gpars.actor.PooledActorGroup

println new PooledActorGroup()

Regarding @GrabResolver also working on import statements, it seems more due to a compiler bug rather than a designed thing.

The compiler lets even the following code compile:

import groovy.beans.*

@Bindable
import org.codehaus.groovy.classgen.*

class Test {}

println Test

where @Bindable is only supposed to be used on field/type targets and nothing else.

Fixed in trunk

Also applied to 1_7_X branch. Both of these should work now:

@GrabResolver(name='jboss', root='http://repository.jboss.org/maven2')
@GrabResolver(name='codehaus.snapshot', root='http://snapshots.repository.codehaus.org')
@Grab('org.codehaus.gpars:gpars:0.9-beta-1')
import groovyx.gpars.actor.*
assert Actors.name.contains('groovyx')

and this:

@Grapes([
  @GrabResolver(name='jboss', root='http://repository.jboss.org/maven2'),
  @GrabResolver(name='codehaus.snapshot', root='http://snapshots.repository.codehaus.org'),
  @Grab('org.codehaus.gpars:gpars:0.9-beta-1')
])
import groovyx.gpars.actor.*
assert Actors.name.contains('groovyx')

Now also in 1.7-rc2