Groovy Mixin use method of mixed class - groovy

Question

Consider a mixin class
class StringPlusMixin {
String plus(String other) {
return toString() + other
}
}
And his use case
#Mixin(StringPlusMixin)
class POGO {
String descr
String toString(){
return descr
}
}
Is there some way to make SringPlusMixin to use POGO#toString() instead of SringPlusMixin#toString() ?
The actual output is:
POGO pogo = new POGO(descr: "POGO description");
System.out.println(pogo + "Some message."); //StringPlusMixin#f410f8 Some message.
I'm considering to use this mixin since the Groovy default of instance + String is to try to call a plus() method. I'm using my POGO in several Java classes and trying to not need to change all messages to use toString().

Answer 1

Use #Delegate transformation in POGO.
#Mixin(StringPlusMixin)
class POGO {
#Delegate String descr
String toString(){
return descr
}
}
Since descr is owned by POGO, in runtime use of descr is delgated to the owner which is POGO.

Answer 2

Reflection? Also, i turned your class into a Category, by making the method static and passing the child object as first parameter.
Update: as per comments, removed the type from the mixin method
import org.codehaus.groovy.runtime.InvokerHelper as Invoker
class StringPlusMixin {
static String plus(pogo, String other) {
def toString = pogo.class.declaredMethods.find { it.name == "toString" }
return toString.invoke(pogo) + other
}
}
#Mixin(StringPlusMixin)
class POGO {
String descr
String toString(){
return descr
}
}
pogo = new POGO(descr: "POGO description")
assert pogo + " Some message." == "POGO description Some message."