[GROOVY-1803] Cannot apply function/closure arguments with defaults

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Won't Fix
• Affects Version/s: 1.0
• Fix Version/s: 1.1-beta-2
• Environment: N/A
• Assignee: Jochen Theodorou
• Reporter: John Redford
• Created: 26/Mar/07 10:34
• Updated: 02/Jul/07 05:03
• Resolved: 02/Jul/07 05:03

Description

The following code demonstrates the problem. It is handy to be able to "apply" arguments to a function/closure, but these calls do not properly handle the presence of default arguments.

def xx =

{ a, b, c = "default" -> println "a $a b $b c $c"; }

;
xx(1, 2, 3);
xx([1, 2, 3]);
z = [1, 2, 3];
xx(z);
z = [1, 2];
xx(1, 2);
xx(z);

def yy (a, b, c = "default")

{ println "a $a b $b c $c"; };
yy(1, 2, 3);
yy([1, 2, 3]);
z = [1, 2, 3];
yy(z);
z = [1, 2];
yy(1, 2);
yy(z);

This would make the following ambiguous:

def zz (a, b = "default", c = "default") { println "a $a b $b c $c"; }

;
zz([1, 2, 3]);

There needs to be a way, as with Java varargs, to indicate when an array is "an array of arguments" and when it is "an argument that is an array".

The current, Java-like approach may not be the best. It would be nice to have an "apply" method on functions/closures that would explicitly take "an array of arguments", much like Scheme/JavaScript:

def zz (a, b = "default", c = "default")

{ println "a $a b $b c $c"; }

;
zz([1, 2, 3]); // "a [1, 2, 3] b default c default"
zz.apply([1,2,3]); // "a 1 b 2 c 3"