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https://issues.apache.org/jira/browse/GROOVY-9003?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16774960#comment-16774960
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paolo di tommaso commented on GROOVY-9003:
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Ouch, was missing this. Not sure it's possible, but what about instead
overriding the toString and equals with using the groovy metaclass for the
Object class in such way it implements the current groovy representation for
collections.
Then subclasses should still be able to provide their own implementation. Does
it make sense ?
> Allow the override of toString and equals methods for collection objects
> -------------------------------------------------------------------------
>
> Key: GROOVY-9003
> URL: https://issues.apache.org/jira/browse/GROOVY-9003
> Project: Groovy
> Issue Type: Improvement
> Reporter: paolo di tommaso
> Priority: Major
> Fix For: 3.x
>
>
> Groovy provides a nice string representation for collection objects, however
> the current behaviour do not allow custom collection classes to provide own
> string representation not to implement a custom object identity rule.
> For example:
> {code:java}
> class Mylist extends ArrayList {
> Mylist(Collection c) { super(c) }
> @Override boolean equals(Object o) { throw new
> UnsupportedOperationException () }
> @Override int hashCode() { throw new UnsupportedOperationException () }
> @Override String toString() { return 'CUSTOM STRING' }
> }
> def l = new Mylist([1,2,3])
> assert l.toString() == 'CUSTOM STRING'
> assert "$l" == '[1, 2, 3]'
> def q = new Mylist([1,2,3])
> assert l.equals(q)
> assert l == q
> {code}
> In the {{Mylist}} class the {{toString}} method is not invoked in the string
> interpolation and {{equals}} is not invoked by the {{==}} operator. This
> breaks the java polymorphism contract and create several hassles when
> implementing custom collection classes.
> I would propose to fix this behaviour in Groovy 3.0. It would be enough to
> check if the target class implements the {{toString}} and {{equals}} methods
> otherwise fallback on the current Groovy behaviour.
>
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