Question

Given:

class FruitBasket {
    int apples = 0
    int oranges = 0
}

I need to pick out apples from each FruitBasket. The work need to be done in processFruit:

def processFruit(list, picker) {
    list.each {
        println "processing " + picker(it)
    }
}

def processAll() {
    List fruitList = [
        new FruitBasket("apples": 2, "oranges": 4),
        new FruitBasket("apples": 3, "oranges": 5)
    ]

    processFruit(fruitList, applePicker)
}

def applePicker(FruitBasket f) {
    return f.getApples()    
}

but it is complaining @ runtime that

No such property: applePicker for class: FooTest

possibly a problem with the closures FruitBasket arg…

Answer 1

In that code, applePicker is a method, not a closure.

You can either use a method handle to pass the method as a parameter like so:

processFruit(fruitList, this.&applePicker)

Or change it to an actual closure:

def applePicker = { FruitBasket f -> return f.getApples()    }