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https://issues.apache.org/jira/browse/GROOVY-11737?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18015402#comment-18015402
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Paul King commented on GROOVY-11737:
------------------------------------
The order as described above is correct in terms of an implementation detail
for selecting whether we have a script, or a traditionally supported main
method script, or a JEP-512 main method. Currently, the particular selected
method isn't remembered, just the fact that a suitable main is there, and then
normal method selection applies. This selection process accounts for
multimethods.
For "normal method selection", inside MetaClassImpl#chooseMethodInternal, there
is special logic that picks the best matching method ("main" method in our
case) when multiple are suitable.
If no arguments are given special matching picks the no-arg variant:
[https://github.com/apache/groovy/blob/master/src/main/java/groovy/lang/MetaClassImpl.java#L3235-L3236]
If an argument is given, the method you expect is matched.
If you have a third main method in that same script:
{code:groovy}
static void main(String a, String b) {
println "3"
}
{code}
And call like this:
{noformat}
groovy main.groovy x y
{noformat}
Then 3 will be printed even though it is never a method that is selected by the
above selection process.
Scripts containing multiple main methods would often be regarded as poor style,
but I agree we should specify/document how we handle that case once determining
whether this is the behavior we want. I'll have a bit more of a think and
potentially start a discussion on the mailing list.
> Understanding Groovy main method priority overloading.
> ------------------------------------------------------
>
> Key: GROOVY-11737
> URL: https://issues.apache.org/jira/browse/GROOVY-11737
> Project: Groovy
> Issue Type: Bug
> Reporter: Georgii Ustinov
> Assignee: Paul King
> Priority: Major
>
> Good afternoon
>
> I am currently trying to support instance main methods inside IntelliJ IDEA
> groovy plugin as a part of Groovy 5 release, however, I can’t find any
> specification of how it works.
>
> I have found that the feature was implemented here -
> [https://github.com/apache/groovy/pull/1910/files].
>
> Looking into the source code -
> [https://github.com/paulk-asert/groovy/blob/90480bfade8c20f935311055e2ceb85288870605/src/main/java/groovy/lang/GroovyShell.java#L275]
> I can see the following order:
>
> 1) static void main(String[] args);
> 2) void main(String[] args);
> 3) static void main(args);
> 4) void main(args);
> 5) static void main();
> 6) void main();
>
> The problem is that it doesn’t correspond to the reality.
>
> Let’s consider the following code main.groovy
>
>
> {code:java}
> void main(args) {
> println "1"
> }
>
> static void main() {
> println "2"
> }
> {code}
>
>
> If I run
> {code:java}
> groovy main.groovy{code}
> 1 will be printed (and it looks correct according to the semantics),
> But if I change example:
>
>
> {code:java}
> void main(String[] args) {
> println "1"
> }
>
> static void main() {
> println "2"
> }
> {code}
> 2 will be printed (and thus the order in the code is violated). But if I run
> {code:java}
> groovy main.groovy someArg{code}
> , then 1 will be printed
>
> Could you, please, provide the correct main method order resolution?
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