Is there an instance in the core language/runtime where a closure literal is
used as part of an annotation but not for an AST transformation? I'm not sure
what the compiler does when it encounters a closure expression as the value for
an annotation attribute (of type Class). But the AST transforms that do this
-- ASTTest and AutoImplement come to mind -- take the closure code and use it
to generate methods. I think GContracts is this way as well.
After reading your example more closely, I see that a single-valued annotation
attribute works as expected but the multi-value case fails.
From: Remko Popma <remko.po...@gmail.com>
Sent: Monday, November 16, 2020 7:02 PM
To: Groovy_Developers <dev@groovy.apache.org>
Subject: Re: Closures in annotations
I’m probably overlooking something simple but I’m not seeing it yet.
The below code demonstrates the issue when trying to pass a Groovy closure to
the @Option(converter = ...)attribute:
class ClosureTest {
static class Demo {
@picocli.CommandLine.Option(names = "-x",
completionCandidates = {["A", "B", "C"]},
converter = [{ str ->
java.security.MessageDigest.getInstance(str) }])
java.security.MessageDigest digest
}
static void main(String[] args) {
def annotation =
Demo.class.getDeclaredField("digest").getAnnotation(picocli.CommandLine.Option)
Class ok = annotation.completionCandidates()
assert ok != null
assert Closure.class.isAssignableFrom(ok)
assert ["A", "B", "C"] == ((Closure) ok.getConstructor(Object,
Object).newInstance(null, null)).call()
Class[] bad = annotation.converter()
assert bad != null
assert bad.length == 1 // this assert fails:
//Exception in thread "main" Assertion failed:
//
//assert bad.length == 1
// | | |
// [] 0 false
//
// at
org.codehaus.groovy.runtime.InvokerHelper.assertFailed(InvokerHelper.java:434)
// at
org.codehaus.groovy.runtime.ScriptBytecodeAdapter.assertFailed(ScriptBytecodeAdapter.java:670)
// at closure.ClosureTest.main(ClosureTest.groovy:18)
}
}
On Mon, Nov 16, 2020 at 21:16 Remko Popma
<remko.po...@gmail.com<mailto:remko.po...@gmail.com>> wrote:
PS
The ITypeConverter interface definition is here:
https://picocli.info/apidocs/picocli/CommandLine.ITypeConverter.html<https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpicocli.info%2Fapidocs%2Fpicocli%2FCommandLine.ITypeConverter.html&data=04%7C01%7Ceric.milles%40thomsonreuters.com%7C1c5e266b8280484ce44c08d88a94782d%7C62ccb8646a1a4b5d8e1c397dec1a8258%7C0%7C0%7C637411717560284723%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=FNAGjAoww3EIKmOnW1kRvE3ZDTQF7k5Ar0Hbo0oHi2k%3D&reserved=0>
On Mon, Nov 16, 2020 at 21:08 Remko Popma
<remko.po...@gmail.com<mailto:remko.po...@gmail.com>> wrote:
Hi all,
I have a question about passing closures to annotations in Groovy.
To illustrate, consider the @Option annotation in the picocli library.
Relevant attributes are `completionCandidates` and `converter`, defined in Java
as follows:
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD, ElementType.METHOD, ElementType.PARAMETER})
public @interface Option {
Class<? extends ITypeConverter<?>>[] converter() default {};
Class<? extends Iterable<String>> completionCandidates() default
NoCompletionCandidates.class;
...
}
I am working on a change to
picocli<https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fremkop%2Fpicocli%2Fissues%2F1258&data=04%7C01%7Ceric.milles%40thomsonreuters.com%7C1c5e266b8280484ce44c08d88a94782d%7C62ccb8646a1a4b5d8e1c397dec1a8258%7C0%7C0%7C637411717560284723%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=AzDZ2%2F5vCf88nV%2BgT3r%2BKBTYW%2BGrrnHUuaduX6ibIsM%3D&reserved=0>
that would allow users to specify closures for these and other attributes.
User code could look like this:
@Option(names = '-s', completionCandidates = {["A", "B", "C"]})
@Field String s
@Option(names = '-a', converter = [{ str -> MessageDigest.getInstance(str) }] )
@Field MessageDigest algorithm
I think this would be a nice addition and would make picocli more "groovy".
I have a prototype implementation, but it appears that only the first example (
completionCandidates = {["A", "B", "C"]} ) works as expected.
When stepping through my prototype test in a debugger, it looks like the second
example (the converter attribute) receives a zero-length array of classes when
invoked from Groovy. I tried with Groovy 2.4.10 and 3.0.6.
Is this a known limitation of Groovy?
Is there a way to work around this?
I can provide an example project to reproduce this if that is helpful.
Kind regards,
Remko
