paolo di tommaso created GROOVY-9003:
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Summary: 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
Fix For: 3.x
Groovy provides a nice string representation for collection objects, however
this implementation do not allow to custom collection class to override their
own string representation.
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 in the target class implements the {{toString}} and {{equals}} methods
otherwise fallback on the current Groovy behaviour.
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