Groovy Closures with exceptions and return values

groovy-closures.groovy

import groovy.transform.InheritConstructors

def doIt(Closure whatToDo) {

    println "hello in doIt"
    def optionalResult = whatToDo.call()
    println "after done it"

    optionalResult
}


void callDoItWithException() {

    try {
        doIt {
            println "my business logic"
            throw new BreakoutOfClosureException("Oh no, a breakout happens")
            println "successfull survived breakout"
        }
    }
    catch (BreakoutOfClosureException e) {
        println e.message
        println "a breakout happend..."
    }
}

int callItWithReturnValues() {
    doIt {
        return 5
    }
}


@InheritConstructors
class BreakoutOfClosureException extends RuntimeException {}

println "----------------"
println "Experiment 1: Exceptions"
callDoItWithException()

println "----------------"
println "Experiment 2: return values"

int resultOfCallItWithReturnValues = callItWithReturnValues()
println "the result is $resultOfCallItWithReturnValues"

println "----------------"

Output

----------------
Experiment 1: Exceptions
hello in doIt
my business logic
Oh no, a breakout happens
a breakout happend...
----------------
Experiment 2: return values
hello in doIt
after done it
the result is 5
----------------