Using ClassLoader to make your game moddable

Roquen · August 8, 2018, 1:23pm

I had made reasonable progress stubbed out a proof-of-concept version of what I described, but sadly didn’t VC it and the drive the code it was on when south. (Yeah I should know better)

Riven · August 10, 2018, 8:41pm

SkyAphid:

To make a whitelist of packages in LuaJ, simply extend LuajavaLib and override this function:
	protected Class<?> classForName(String name) throws ClassNotFoundException {
		Class<?> clazz = Class.forName(name, true, ClassLoader.getSystemClassLoader());

		return (isInWhitelist(clazz) ? clazz : null);
	}

Nooooooo :point:

Class.forName(…) actually executes the static-blocks of the class, if not already loaded.

If you want to whitelist classes, you’d check isInWhitelist(String name), not isInWhitelist(Class clazz)

nsigma · August 11, 2018, 9:30am

Ironic to use the 3-argument version and then not pass in false, which at least might make it vaguely safe!

… yes, use String!

bullen · August 12, 2018, 10:17am

I use this for the server part of my multiplayer engine so I can hot-deploy to a cluster of machines asynchronously:

github.com

tinspin/rupy/blob/master/src/se/rupy/http/Deploy.java

package se.rupy.http;

import java.io.*;
import java.lang.reflect.ReflectPermission;

import javax.net.ssl.SSLPermission;

import java.net.*;
import java.nio.file.LinkPermission;
import java.security.*;
import java.text.SimpleDateFormat;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.jar.*;

/**
 * Hot-deploys an application containing one or many service filters from disk
 * with simplistic dynamic class loading, eventually after receiving it through
 * a HTTP POST.
 * <pre>

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But if you are developing locally you can hot-reload code changes, I think something from here should work: