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://github.com/remkop/picocli/issues/1258> 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
