String.metaClass.length = {-> return 1}

I say “normally” as there’s actually a weird bug/issue in groovy that affects this particular test case to not make it work (that I wasn’t previously aware of). Apparently, in the 1.7 versions of groovy, there’s a bug that causes any method that is part of an interface to not be overridden by the metaClass. Most groovy stuff doesn’t use interfaces so it’s normally not that big of a deal, but it is a big deal with Java stuff.

So I’m able to override this zero param length method with no problem because it isn’t part of an interface:

class Bar {
    int length() {
        return 3
    }
}
 
def b = new Bar()
 
assert 3 == b.length()
 
b.metaClass.length = {-> return 1}
 
assert 1 == b.length()

But String.length() gets put onto the String class because length() is an implementation of a method from the CharSequence interface.

String.metaClass.concat = { String s ->
println ‘Coming herere >>>>>>>>>>>>> ‘
return 1
}
String.metaClass.length = {
println ‘Coming herere >>>>>>>>>>>>> ‘
return 1
}

println “Foo”.concat(“bar”)
println “Foo”.length()

Expected result :

Coming herere >>>>>>>>>>>>>
1
Coming herere >>>>>>>>>>>>>
1

But result produced is :

Coming herere >>>>>>>>>>>>>
1
3

Do you have any idea how to override methods that doesn’t take parameters ?

Cheers!

-Deepak

Cheers,
Josh