[GROOVY-7037] getAt as Operator Throws if given Fixed and Variable Arguments

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 2.3.6, 2.4.0-beta-2
• Labels: varargs
• Environment: RHEL 6.5 x64
• Assignee: Unassigned
• Reporter: Steve Amerige
• Created: 22/Aug/14 07:40
• Updated: 19/Nov/21 16:54

Description

The getAt method for indexing fails when variable arguments are used with [] if any fixed arguments are present. For example:

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
   }
}

The above produces:

Exception thrown
java.lang.IllegalArgumentException: wrong number of arguments
	at Test.main(ConsoleScript42:14)

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.