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https://issues.apache.org/jira/browse/GROOVY-7037?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15445582#comment-15445582
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Paul King commented on GROOVY-7037:
-----------------------------------
In some sense this isn't specific to {{getAt}}. Consider this code:
{code}
import static groovy.test.GroovyAssert.shouldFail
class Test {
def x(String s, Integer i) { "1:$s $i" }
def x(String s, Integer... is) { "2:$s $is" }
}
assert new Test().x('a', 1) == '1:a 1' // (1)
assert new Test().x('b') == '2:b []' // (2)
assert new Test().x('c', 2, 3) == '2:c [2, 3]' // (2)
assert new Test().x('d', 4, 5, 6) == '2:d [4, 5, 6]' // (2)
assert new Test().x(['e', 7]) == '1:e 7' // (3)
def ex = shouldFail(IllegalArgumentException) {
new Test().x(['f', 8, 9]) // (4)
}
assert ex.message == 'wrong number of arguments'
{code}
Groovy does normal argument matching, giving preference to non-varargs matches
(1) but matching varargs if needed (2).
Also, if a list argument is provided and no method with a list parameter is
found, an attempt is made to spread the list which matches if a method having
the correct number and types of arguments can be found (3). But in the case of
varargs, with a list argument, then the IllegalArgumentException can occur.
Unfortunately for the shorthand {{getAt}} syntax, the arguments are always
wrapped in a list, so the chances are higher of seeing this error..
> getAt as Operator Throws if given Fixed and Variable Arguments
> --------------------------------------------------------------
>
> Key: GROOVY-7037
> URL: https://issues.apache.org/jira/browse/GROOVY-7037
> Project: Groovy
> Issue Type: Bug
> Affects Versions: 2.3.6, 2.4.0-beta-2
> Environment: RHEL 6.5 x64
> Reporter: Steve Amerige
> Priority: Minor
> Attachments: Test.groovy
>
>
> The getAt method for indexing fails when variable arguments are used with []
> if any fixed arguments are present. For example:
> {code}
> class Test
> {
> def getAt(String s) { return s }
> def getAt(String s, Integer x) { return "$s $x" }
> // def getAt(Object... o) { return o } // This would succeed
> def getAt(String s, Object... a) { return "$s $a" }
> static void main(String[] args)
> {
> Test t = new Test()
> assert t['a'] == 'a'
> assert t['b', 2] == 'b 2'
> assert t.getAt('c', 3, true) == 'c [3, true]'
> assert t['c', 3, true] == 'c [3, true]' // This throws an exception
> }
> }
> {code}
> The above produces:
> {noformat}
> Exception thrown
> java.lang.IllegalArgumentException: wrong number of arguments
> at Test.main(ConsoleScript42:14)
> {noformat}
> Workaround: do not use fixed and variable arguments at the same time and use
> only variable arguments as in the case shown commented out above:
> getAt(Object... o). This is less-than desirable, however, because it
> restricts the user from using method overloading to separate out
> distinctly-different logic and forces the user to do runtime checks and
> implement control structure when using the single varargs method. In this
> case, however, the bug severity is mitigated by the fact that the user can
> explicitly use the "getAt" invocation instead of using the [ ] operator
> notation.
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