Efficient way to run multiple scripts using javax.script

Question

I am developing a game where I'd like to have multiple scripts that all implement the same structure. Each script would need to be run in its own scope so that code doesn't overlap other scripts. For example:

structure.js

function OnInit() {
    // Define resources to load, collision vars, etc.
}

function OnLoop() {
    // Every loop
}

function ClickEvent() {
   // Someone clicked me
}

// Other fun functions

Now, lets say I have: "BadGuy.js", "ReallyReallyBadGuy.js", "OtherBadGuy.js" - They all look like the above in terms of structure. Within the game whenever an event takes place, I'd like to invoke the appropriate function.

The problem comes down to efficiency and speed. I found a working solution by creating an engine for each script instance (using getEngineByName), but that just doesn't seem ideal to me.

If there isn't a better solution, I'll probably resort to each script having its own unique class / function names. I.e.

BadGuy.js

var BadGuy = new Object();

BadGuy.ClickEvent = function() {
}

Answer 1

I don't think you need to create a new ScriptEngine for every "Guy". You can manage them all in one engine. So with advance apologies for butchering you game scenario.....

1. Get one instance of the Rhino engine.
2. Issue eval(script) statements to add new JS Objects to the engine, along with the different behaviours (or functions) that you want these Objects to support.
3. You have a couple of different choices for invoking against each one, but as long as each "guy" has a unique name, you can always reference them by name and invoke a named method against it.
4. For more performance sensitive operations (perhaps some sort of round based event loop) you can precompile a script in the same engine which can then be executed without having to re-evaluate the source.

Here's a sample I wrote in Groovy.

import javax.script.*;
sem = new ScriptEngineManager();
engine = sem.getEngineByExtension("js");
engine.getBindings(ScriptContext.ENGINE_SCOPE).put("out", System.out);
eventLoop = "for(guy in allGuys) { out.println(allGuys[guy].Action(action)); }; "
engine.eval("var allGuys = []");
engine.eval("var BadGuy = new Object(); allGuys.push(BadGuy); BadGuy.ClickEvent = function() { return 'I am a BadGuy' }; BadGuy.Action = function(activity) { return 'I am doing ' + activity + ' in a BAD way' }");
engine.eval("var GoodGuy = new Object(); allGuys.push(GoodGuy); GoodGuy.ClickEvent = function() { return 'I am a GoodGuy' }; GoodGuy.Action = function(activity) { return 'I am doing ' + activity + ' in a GOOD way' }");
CompiledScript executeEvents = engine.compile(eventLoop);
println engine.invokeMethod(engine.get("BadGuy"), "ClickEvent");
println engine.invokeMethod(engine.get("GoodGuy"), "ClickEvent");
engine.getBindings(ScriptContext.ENGINE_SCOPE).put("action", "knitting");
executeEvents.eval();