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https://issues.apache.org/jira/browse/GROOVY-8363?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16214117#comment-16214117
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Kevin Chen edited comment on GROOVY-8363 at 10/21/17 10:15 PM:
---------------------------------------------------------------
Are you sure that's quite right? Calling the delegate does involve finding its
{{.size()}} because of the {{.collect()}}, but that shouldn't invoke a
recursive call -- the reference there isn't to the {{getDelegate()}}; it's
directly to the {{List}} itself.
The problem with your suggested implementation (and maybe you just didn't want
to type this out) is that I want to be able to call methods like {{.size()}}
and {{.collect()}} and {{.find()}}, etc. on the delegating list itself.
Currently, I solve this issue by only removing the {{implements List<String}}
part and retaining all of the other methods (and thus creating this ugly
interface sort of file that's just a copy of {{List}}). If you want to check
out the example git repository, I've also pushed a version demonstrating
exactly that.
was (Author: aspin):
Are you sure that's quite right? Calling the delegate does involve finding its
{{.size()}} because of the {{.collect()}}, but that shouldn't invoke a
recursive call -- the reference there isn't to the {{getDelegate()}}; it's
directly to the {{List}} itself.
The problem with your suggested implementation (and maybe you just didn't want
to type this out) is that I want to be able to call methods like {{.size()}}
and {{.collect()}} and {{.find()}}, etc. on the delegating list itself.
Currently, I solve this issue by only remove the {{implements List<String}}
part and retaining all of the other methods (and thus creating this ugly
interface sort of file that's just a copy of {{List}}). If you want to check
out the example git repository, I've also pushed a version demonstrating
exactly that.
> Implementing List with a delegated data source results in
> StackOverflowException
> --------------------------------------------------------------------------------
>
> Key: GROOVY-8363
> URL: https://issues.apache.org/jira/browse/GROOVY-8363
> Project: Groovy
> Issue Type: Bug
> Reporter: Kevin Chen
>
> Preface: not experienced with submitting bugs to the Groovy project, so
> please bear with me if anything's unclear.
> I'm getting a StackOverflowException from this bit of code (I think just
> including this snippet demonstrates better than I can explain verbally):
> {code:title=DelegateList.groovy|borderStyle=solid}
> class DelegateList {
> private List<String> lowerCaseStrings = []
> private DelegatingListImplementation uppercaseStrings = new
> DelegatingListImplementation()
> private abstract static class DelegatingList implements List<String> {
> abstract List<String> getDelegate()
> @Override
> int size() {
> return delegate.size()
> }
> @Override
> boolean isEmpty() {
> return delegate.isEmpty()
> }
> // etc.
> }
> private class DelegatingListImplementation extends DelegatingList {
> @Override
> List<String> getDelegate() {
> return lowerCaseStrings.collect { it.toUpperCase() }
> }
> }
> DelegateList(Collection<String> strings) {
> lowerCaseStrings = strings.toList().collect { it.toLowerCase() }
> }
> List<String> getUppercase() {
> return uppercaseStrings
> }
> public static void main(String[] args) {
> def d = new DelegateList(['hello', 'bye'])
> println d.getUppercase() // StackOverflowError
> }
> }
> {code}
> The equivalent doesn't happen in Java. Example repository with both runnables
> is here: [https://github.com/aspin/groovy-delegate-list]. I'm not really sure
> how to get deeper into the source of this (Groovy's closure resolving
> strategies?) and/or how to work around.
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