In general the Nashorn docs start here.
https://wiki.openjdk.java.net/display/Nashorn/Nashorn+Documentation, but as you
point out, we seem to be lacking JSAdapter details. I should start an FAQ.
From the javadoc (cd make; ant javadoc # ./dist/javadoc/index.html)
public final class NativeJSAdapter
extends ScriptObject
This class is the implementation of the Nashorn-specific global object named
JSAdapter. It can be thought of as the Proxy equivalent for JavaScript.
NativeJSAdapter calls specially named JavaScript methods on an adaptee object
when property access/update/call/new/delete is attempted on it. Example:
var y = {
__get__ : function (name) { ... }
__has__ : function (name) { ... }
__put__ : function (name, value) {...}
__call__ : function (name, arg1, arg2) {...}
__new__ : function (arg1, arg2) {...}
__delete__ : function (name) { ... }
__getIds__ : function () { ... }
};
var x = new JSAdapter(y);
x.i; // calls y.__get__
x.foo(); // calls y.__call__
new x(); // calls y.__new__
i in x; // calls y.__has__
x.p = 10; // calls y.__put__
delete x.p; // calls y.__delete__
for (i in x) { print(i); } // calls y.__getIds__
JavaScript caller of adapter object is isolated from the fact that the property
access/mutation/deletion are really calls to JavaScript methods on adaptee.
JSAdapter constructor can optionally receive an "overrides" object. Properties
of overrides object is copied to JSAdapter instance. When user accessed
property is one of these, then adaptee's methods like __get__, __put__ etc. are
not called for those. This can be used to make certain "preferred" properties
that can be accessed in the usual/faster way avoiding proxy mechanism. Example:
var x = new JSAdapter({ foo: 444, bar: 6546 }) {
__get__: function(name) { return name; }
};
x.foo; // 444 directly retrieved without __get__ call
x.bar = 'hello'; // "bar" directly set without __put__ call
x.prop // calls __get__("prop") as 'prop' is not overridden
It is possible to pass a specific prototype for JSAdapter instance by passing
three arguments to JSAdapter constructor. So exact signature of JSAdapter
constructor is as follows:
JSAdapter([proto], [overrides], adaptee);
Both proto and overrides are optional - but adaptee is not. When proto is not
passed JSAdapter.prototype is used.
As well as the test ./test/script/basic/jsadapter.js
var obj = new JSAdapter() {
__get__: function(name) {
print("getter called for '" + name + "'"); return name;
},
__put__: function(name, value) {
print("setter called for '" + name + "' with " + value);
},
__call__: function(name, arg1, arg2) {
print("method '" + name + "' called with " + arg1 + ", " + arg2);
},
__new__: function(arg1, arg2) {
print("new with " + arg1 + ", " + arg2);
},
__getIds__: function() {
print("__getIds__ called");
return [ "foo", "bar" ];
},
__getValues__: function() {
print("__getValues__ called");
return [ "fooval", "barval" ];
},
__has__: function(name) {
print("__has__ called with '" + name + "'");
return name == "js";
},
__delete__: function(name) {
print("__delete__ called with '" + name + "'");
return true;
}
};
// calls __get__
print(obj.foo);
// calls __put__
obj.foo = 33;
// calls __call__
obj.func("hello", "world");
// calls __new__
new obj("hey!", "it works!");
for (i in obj) {
print(i);
}
for each (i in obj) {
print(i);
}
var x = "foo" in obj;
print(x);
var y = "js" in obj;
print(y);
print(delete obj.prop);
print(obj["js"]);
obj["js"] = "javascript";
print(obj["javascript"]);
Hope that helps. Is there a specific question?
Cheers,
-- Jim
On 2013-10-22, at 11:50 AM, Rick Bullotta <rick.bullo...@thingworx.com> wrote:
> Hi, all.
>
> I've been searching everywhere for any form of documentation or substantive
> examples as to how JSAdapter works in Nashorn, as it is an essential piece of
> the puzzle for many of us who will naturally be migrating from Rhino.
>
> Can anyone provide and additional info?
>
> Thanks,
>
> Rick
> ThingWorx
>
