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https://issues.apache.org/jira/browse/GROOVY-11118?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17738513#comment-17738513
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Paul King commented on GROOVY-11118:
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Yes, correct, currently static {{main}} needs {{Object}} or {{String[]}} args.
I was proposing to expand that to also handle the no-args case.
We do have the option making instance {{main}} also be a script but there are
some advantages to the JEP-445 approach where it doesn't need {{@Field}} for
instance. So long as we can clearly explain what we are supporting, I think we
can give users both options. But yes, that is one of the design options open
for discussion.
> Partial JEP 445 compatibility
> -----------------------------
>
> Key: GROOVY-11118
> URL: https://issues.apache.org/jira/browse/GROOVY-11118
> Project: Groovy
> Issue Type: New Feature
> Reporter: Paul King
> Assignee: Paul King
> Priority: Major
> Labels: GEP
> Fix For: 5.x
>
>
> [JEP 445: Unnamed Classes and Instance Main
> Methods|https://openjdk.org/jeps/445] provides features that improve using
> Java for scripting purposes. While these features offer a subset of the
> features offered by Groovy for scripting, it would be nice to offer some
> interworking for cut-n-paste compatibility and leveraging the updated launch
> protocol.
> (i) This description will contain the most update-to-date proposal for the
> design but may undergo change during discussions. If needed, a separate GEP
> section in the wiki will capture the final design.
> h2. Scripting semantics
> ||Source file characteristics||Semantics determined||
> | Contains class declaration | Compiled as a class |
> | Contains uncontained non-declaration statements
> or a static main method | Compiled as a Groovy script |
> | Contains an instance main method, and
> possibly field and other method declarations | Compiled as a JEP 445
> compatible class |
> Groovy scripts are wrapped into an encompassing class that extends
> {{groovy.lang.Script}}.
> Such classes have a {{public static void main}} added which (summarising)
> creates a class instance and calls its {{run}} method.
> Uncontained statements within the script can be though of as belonging within
> the {{run}} method.
> Declaration statements within the script are treated as local variable
> definitions (also within the {{run}} method).
> Field definitions can be obtained by annotating declaration statements with
> the {{@Field}} annotation.
> JEP 445 scripts do not extend {{Script}} and do not have any methods added.
> Declaration statements within the script are treated as field definitions.
> h2. Script runner
> Groovy's runner mechanism will be extended to follow a similar protocol to
> Java's revised launch protocol. This should be available for JDK11+ and a
> JEP-445 compatible class could be invoked using JDK21+ with preview enabled
> (with Groovy on the classpath unless a POJO class is created).
>
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