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https://issues.apache.org/jira/browse/GROOVY-10192?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17752191#comment-17752191
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Eric Milles commented on GROOVY-10192:
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GROOVY-9510 has examples of DSLD and GDSL for {{Requires}}, {{IgnoreIf}},
{{PendingFeatureIf}} and {{Retry}}. There is also discussion of the
{{getInstance()}} and {{getShared()}} methods -- {{DelegatesTo}} will not help
work out their return types.
I removed the method target that was added to {{DelegatesTo}} in this commit
since it was never leveraged by STC. It could be added back if needs be and I
think {{ClosureParams}} should get the same treatment.
https://github.com/apache/groovy/commit/5f8c82e9c88bb7087bdf134f2864d7ca9008b9e7
> Smarter Closure delegation detection in annotation parameters
> -------------------------------------------------------------
>
> Key: GROOVY-10192
> URL: https://issues.apache.org/jira/browse/GROOVY-10192
> Project: Groovy
> Issue Type: Improvement
> Components: Compiler
> Affects Versions: 3.0.8, 4.0.0-alpha-3
> Reporter: Marcin Zajaczkowski
> Priority: Minor
> Labels: annotations
>
> TL;TR. I would like to have a way to inform IDE that a passed in an
> annotation Closure's execution is in fact delegated to a specific object
> (type). E.g. "@Requires(\{ jvm.java11 })" should allow to write "jv" and see
> jvm in IDE (once a delegate has that field/getter).
> More detailed version (based on my question on the mailing list in [January
> 2020|https://mail-archives.apache.org/mod_mbox/groovy-users/202001.mbox/%[email protected]%3e]).
> One of the nice features of Spock is an ability to define conditions in
> Closure when test(s) should (not) be executes with @Required/@IgnoreIf.
>
> {code:java}
> @Requires({ isSpecialConditionFulfilled() })
> def "some test"() {}
> {code}
> The annotation itself is defined as:
>
> {code:java}
> @Retention(RetentionPolicy.RUNTIME)
> @Target({ElementType.TYPE, ElementType.METHOD})
> @ExtensionAnnotation(RequiresExtension.class)
> public @interface Requires {
> Class<? extends Closure> value();
> }
> {code}
> Down the line the execution is delegated to PreconditionContext which
> provides convenient methods/objects such as os.linux, jvm.java11, env, etc.
> {code:java}
> @Requires({ jvm.java11 && os.linux }) {code}
> Unfortunately, there is no code completion as IDE doesn't know about
> that delegation (and jvm, os fields/methods). Groovy 2 introduced
> @DelegatesTo, however it cannot be used with other annotations or methods.
> It can be tricked by creating a static final instance of PreconditionContext
> (it's stateless) somewhere (e.g. in the Specification super class), but
> people has to know to refer it, e.g:
> {code:java}
> @Requires({ CTX.jvm.java11 }){code}
> Alternatively, I was thinking about a method in the base Spock class:
> {code:java}
> protected static def ctx(@DelegatesTo(PreconditionContext) Closure closure) {
> closure()
> }{code}
> which could be referenced as:
> {code:java}
> @Requires({ ctx { jvm.java10Compatible } }){code}
> It works, but again "ctx" has to be referenced on demand.
> The best long-term solution would be to allow to use @DelegatesTo at the
> method level:
> {code:java}
> public @interface MyRequires {
> @DelegatesTo(PreconditionContext.class) Class<? extends Closure> value();
> } {code}
> It would provide code completion out of the box (once IDEs have support for
> that ). The second main drawback I see is being not very intuitive
> declaration and limited usage.
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