[ 常見問題 ] Named parameters for Closure/Method

Source From Here 
Question 
I have method 

view plaincopy to clipboardprint?

1. def test(String a, String b) { }  

and I would like to call this with a dynamic parameter map. I always though that: 

view plaincopy to clipboardprint?

1. test(['1','2']); //valid call  

and also 

view plaincopy to clipboardprint?

1. test([a:'1',b:'2']); //=> does not work  

will work. but it doesn't. So I remembered the spread operator, but can't get it to work.... 

Is there a way to call a method like the one above with some kind of map as parameter instead of single parameters? 

How-To 
Maybe I missed something, but I don't think Groovy has named parameters right now. There are discussions and proposals, but I'm not aware of anything official. For your case, I think the map spread may help, but not in every case. Upon getting the values, it follows the order in which the map values were declared: 

view plaincopy to clipboardprint?

1. package howto  
2.   
3. def test(String a, String b) { "a=$a, b=$b" }  
4. def test(Map m) { test m*.value }  
5.   
6. class Obj{  
7.     public String test(String a="a", String b="b"){ return "a=$a, b=$b" }  
8. }  
9.   
10. assert test(a: "aa", b:"bb") == "a=aa, b=bb"  
11. assert test(b: "aa", a:"bb") == "a=aa, b=bb" // should be false :-(  
12. assert test(b: "ccc", a:"ddd") == "a=ccc, b=ddd" // should have worked :-(  
13.   
14. Obj o = new Obj()  
15. assert o.test("aa", "bb") == "a=aa, b=bb"  
16. assert o.test(*["ccc", "ddd"]) == "a=ccc, b=ddd"  
17.   
18. def otest = o.&test  
19. assert otest("aa", "bb") == "a=aa, b=bb"  
20. assert otest(*["ccc", "ddd"]) == "a=ccc, b=ddd"  
21.   
22. printf("Done!\n")  

Supplement 
* [ GroovyGN ] Turn Methods into Closures 
* [ Groovy Doc ] Dynamic Groovy 
* [ In Action ] Dynamic object orientation - Defining classes and scripts