[GROOVY-3917] getProperty isn't delegated more than 1 level deep

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 1.6.4
• Component/s: groovy-runtime
• Environment: Mac OSX, 10.5.8
• Assignee: Unassigned
• Reporter: luke sydenham
• Created: 01/Dec/09 11:36
• Updated: 10/May/21 22:27

Description

I have a type A that defines the getProperty magic method. It is declared as a delegate in a class called B. The getProperty method is not redefined in B so whenever getProperty is called on an instance of B it delegates the request to A which then handles the request as expected. If I then have a class C that declares a delegate of type B and also does not redefine the getProperty method, I would expect that when you call getProperty on an instance of C that it would delegate to its instance of type B, which would in turn delegate the request to its instance of type A and the request would be handled.

Unfortunately, this does not happen. Class C says it does not have a property with the name requested. If I then define getProperty in C but simply return b.getProperty(somePropertyName) in the method (explicitly defining the delegation) then groovy handles the delegation. Does this mean that delegation only works 1 level deep?

See example below where C does delegation of getProperty explicitly (this works)

class C {
    @Delegate B b = new B()

    public getProperty(String name) {
        return b.getProperty(name)
    }

    static void main(args) {
        def c = new C()

        System.out.println(c.hello)
    }
}

class B {
    @Delegate A a = new A()
}

class A {
    public getProperty(String name) {
        return name
    }
}

... and implicitly (this doesn't work)

class C {
    @Delegate B b = new B()

    static void main(args) {
        def c = new C()

        System.out.println(c.hello) //throws an unknown property exception
    }
}

class B {
    @Delegate A a = new A()
}

class A {
    public getProperty(String name) {
        return name
    }
}