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https://issues.apache.org/jira/browse/GROOVY-8952?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16737024#comment-16737024
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Paul King commented on GROOVY-8952:
-----------------------------------
The code has always (well, at least since 2007) handled closures specially to
allow lazy processing in those rare cases when it does make sense:
https://github.com/apache/groovy/blob/master/src/main/groovy/groovy/lang/GString.java#L184
I am unsure whether the above is your real use case or a cut down version. If
we understood what you were really trying to do, perhaps we could suggest some
alternatives for you.
> Eager interpolation evaluating as a Closure does a lazy invoke of the Closure
> -----------------------------------------------------------------------------
>
> Key: GROOVY-8952
> URL: https://issues.apache.org/jira/browse/GROOVY-8952
> Project: Groovy
> Issue Type: Bug
> Affects Versions: 2.5.5
> Environment: Windows 10
> Reporter: Chaitanya Birudavolu
> Priority: Major
> Labels: closure, eager, interpolation
>
> This is regarding the eager interpolation placeholder
> {code:java}
> ${ <expression> }{code}
> The expected behavior is that the expression would be evaluated eagerly (at
> GString creation time). Later, at GString coercion time, the value that is
> expected in the place of the eager placeholder is the result of
> {code:java}
> <expression>.toString(){code}
>
>
> This works most of the time, but doesn't seem to work if the expression
> evaluates to a Closure type. If the expression evaluates to a Closure type,
> what is observed is that, in the place of the placeholder, instead of seeing
> ...
> {code:java}
> <closure>.toString(){code}
> ... we see...
> {code:java}
> <closure-invocation-result>.toString(){code}
> For example, in the below code...
>
> {code:java}
> def c = {->println ('Inside closure')}
> println ('Just before creating the GString')
> def gstr = "${println ('Inside eager placeholder'); 20; 30; c}"
> println ('Just after creating the GString')
> println (gstr)
> {code}
>
> ...the expected behavior is that the closure should never get executed, and
> the last println should only print the result of
> {code:java}
> c.toString(){code}
> Instead, the last line printed is observed to be:
> {code:java}
> Inside closure{code}
>
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