Come aggiungere una nuova chiusura a una classe in groovy
-
10-07-2019 - |
Domanda
Da Snipplr
Ok ecco il codice dello script, nei commenti c'è la domanda e l'eccezione generata
class Class1 {
def closure = {
println this.class.name
println delegate.class.name
def nestedClos = {
println owner.class.name
}
nestedClos()
}
}
def clos = new Class1().closure
clos.delegate = this
clos()
//Now I want to add a new closure to Class1
def newClosure = {
println "new Closure"
println this.class.name
println delegate.class.name
def nestedClos = {
println owner.class.name
}
nestedClos()
}
//getAbc to create a property, not a method
Class1.metaClass.getAbc = newClosure
//What happens here is that the property abc is not used as a closure per se, it's used
//as a property and when I execute it just run the closure and when I want to change
//the delegate, a null pointer is thrown
clos = new Class1().abc //abc executed instead of passing the reference closure
clos.delegate = this //Exception!!!!
clos()
Soluzione
Ok, non è un modo elegante, ma ho la soluzione .... sì!
Crea la proprietà come oggetto e successivamente assegna la chiusura
class Class1 {
def closure = {
println this.class.name
println delegate.class.name
def nestedClos = {
println owner.class.name
}
nestedClos()
}
}
def clos = new Class1().closure
clos.delegate = this
clos()
//Now I want to add a new closure to Class1
def newClosure = {
println "new Closure"
println this.class.name
println delegate.class.name
def nestedClos = {
println owner.class.name
}
nestedClos()
}
//before edit
//Class1.metaClass.abc = new Object()
Class1.metaClass.abc = newClosure
def cl = new Class1()
//Before edit
//For the sake of simplicity we are going to use & for the method
//clos = cl.abc
closs = cl.&abc
clos.delegate = this
clos()
Autorizzato sotto: CC-BY-SA insieme a attribuzione
Non affiliato a StackOverflow