samples/jsobj_example.js

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// Flexible script object using AbstractJSObject subclass

var AbstractJSObject = Java.type("jdk.nashorn.api.scripting.AbstractJSObject");

// JSObject example that uses a map for properties and
// falls back to with methods on a java object (for missing
// properties

function makeJSObj(map, fallback) {
    return new AbstractJSObject() {
        getMember: function(name) {
            if (map.containsKey(name)) {
                return map.get(name);
            }

            var val = fallback[name];
            if (typeof val == 'function') {
                return function() {
                   var a = arguments;
                   switch (a.length) {
                       case 0: return fallback[name]();
                       case 1: return fallback[name](a[0]);
                       case 2: return fallback[name](a[0], a[1]);
                       case 3: return fallback[name](a[0], a[1], a[2]);
                       case 4: return fallback[name](a[0], a[1], a[2], a[3]);
                   }
                }
            }
        }
    }
}

var m = new java.util.HashMap();
m.put("foo", 42);
m.put("bar", 'hello');

var obj = makeJSObj(m, new java.io.File("."));

print(obj.foo);
print(obj.bar);
print(obj.getAbsolutePath());
print(obj.isDirectory());