[
https://issues.apache.org/jira/browse/GROOVY-11548?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17910517#comment-17910517
]
Paul King edited comment on GROOVY-11548 at 1/7/25 7:14 AM:
------------------------------------------------------------
This is kind of by design (well, an implementation detail in Groovy 4). Groovy
5 compiles default interface methods natively. Groovy 4 emulates them with
traits. So, your interface (because it has a default method) is converted to:
{code:groovy}
trait I0 {
void func() { }
}
{code}
And the semantics of traits is to override rather than be a default. Groovy 5
lets you pick between traits and default methods in interfaces so you get the
best of both worlds depending on your needs. The workaround in Groovy 4 is to
write just that one interface in Java.
Another workaround would be to use {{{}@Delegate{}}}:
{code:groovy}
class A {
final void func() {
println 'A::func'
}
}
interface I0 {
default void func() {
println 'IO::func'
}
}
class B implements I0 {
@Delegate A a = new A()
}
new B().func() // => A::func
{code}
was (Author: paulk):
This is kind of by design (well, an implementation detail in Groovy 4). Groovy
5 compiles default interface methods natively. Groovy 4 emulates them with
traits. So, your interface (because it has a default method) is converted to:
{code:groovy}
trait I0 {
void func() { }
}
{code}
And the semantics of traits is to override rather than be a default. Groovy 5
lets you pick between traits and default methods in interfaces so you get the
best of both worlds depending on your needs. The workaround in Groovy 4 is to
write just that one interface in Java.
> Could not inherit class and interface where class has a final method
> overridden by interface
> --------------------------------------------------------------------------------------------
>
> Key: GROOVY-11548
> URL: https://issues.apache.org/jira/browse/GROOVY-11548
> Project: Groovy
> Issue Type: Bug
> Components: Compiler
> Affects Versions: 4.0.24
> Environment: Tried on Linux and Windows, the same error.
> Reporter: Xiaotian Ma
> Assignee: Paul King
> Priority: Major
> Fix For: 5.0.0-alpha-11
>
>
> Compile following code.
> {code:groovy}
> class A {
> final public void func() {
> }
> }
> interface I0 {
> public default void func() {
> }
> }
> class B extends A implements I0 {
> }{code}
> Groovy 4.0.24:
> {code:java}
> A.groovy: -1: You are not allowed to override the final method func() from
> class 'A'.
> @ line -1, column -1.
> 1 error{code}
> Groovy 5.0.0-alpha-11: passed
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
