luajc loader with tomcat

manaldush — Mon, 21 Aug 2017 14:01:50 -0000

Hello!
Please somebody help.
I am trying to use luaj in my webapp with tomcat.
All ok!
But when i try to use java compilation with luajc, I have errors when i execute loadfile command

            env = JsePlatform.standardGlobals();
            LuaJC.install(env);
            luaFile = env.loadfile(script);

org.luaj.vm2.LuaError: load test2.lua: org.luaj.vm2.LuaError: load @test2.lua: java.lang.IllegalStateException: bad class gen: java.lang.ClassCastException: test2 cannot be cast to org.luaj.vm2.LuaFunction
at org.luaj.vm2.LuaValue.error(Unknown Source)
at org.luaj.vm2.Globals.loadfile(Unknown Source)
at com.peterservice.openapi.pccm.lua.LuaEngine.innerInit(LuaEngine.java:212)
at com.peterservice.openapi.pccm.lua.LuaEngine.reload(LuaEngine.java:71)

My test2.lua file is elementary

print("Hello world")

I can not undestand what is a problem.

Lua 5.3?

James Upjohn — Wed, 26 Apr 2017 01:21:09 -0000

It would seem that this project is not actively maintained - much to many people's dissapointment. It still works, but I'm afraid a 5.3 update is unlikely.

Lua 5.3?

De Vlaam — Sun, 03 Jul 2016 16:47:29 -0000

Are there plans to update this lib to version 5.3 of the language spec? This would be worthwhile since Luaj seems to be the most advanced Java implementation of Lua sofar.

How to evaluate expression from android java ?

Cyril Preiss — Sun, 29 May 2016 13:57:15 -0000

Hi,

i have a simple script:

"var_face = 2"

I didn't find out how to get the result of this expression from my java app:
""var_face == 3 and 100 or -1""

i have started with this:
Globals globals = JsePlatform.standardGlobals();
LuaValue chunk = globals.load(script);
chunk.call();

    String result = chunk.call("var_face == 3 and 100 or -1").toString();

    but i'm getting "nil"

java.lang.ClassNotFoundException

gmeqiminfo — Mon, 29 Feb 2016 14:07:11 -0000

to help someone :

we modifiy LuajavaLib class to add web-app class loader

// load classes using app loader to allow luaj to be used as an extension
protected Class<?> classForName(String name) throws ClassNotFoundException{

    Class<?> c = null;
    try {
        c = Class.forName(name, true, ClassLoader.getSystemClassLoader());
    } catch (ClassNotFoundException e) {
        c = Class.forName(name, true, this.getClass().getClassLoader());
    }
    return c;
}

No more non-speaking "Attempt to call nil" messages :)

gmeqiminfo — Mon, 29 Feb 2016 13:57:59 -0000

Thank you for this help.

But in our environnement we needed to modify LuaScriptEngine BindingsMetatable class and put this ack to show which function is not defined :

this.rawset(LuaValue.INDEX, new TwoArgFunction() {
    public LuaValue call(LuaValue table, LuaValue key) {

        if (key.isstring()) {
            Object o = bindings.get(key.tojstring());
            if(o == null){
                return Lua.namedNil( key );
            } else {
                return toLua(o);
            }
        }
        else
            return this.rawget(key);
    }
});

How to test Luaj?

gsnerf — Fri, 25 Sep 2015 07:24:33 -0000

I've come across the same problem. I've found that you need to download the maven ant tasks (i.e. from here: http://apache.mirror.digionline.de/maven/ant-tasks/2.1.3/binaries/ ) and place it into the lib directory for ant. It seems it downloads some dependencies through maven. Unfortunately thats not the last of it, as it will fail later saying it doesn't know the target luaj1-lib (which it can't because it isn't declared anywhere). I've got the feeling the tests aren't really up to date and propably won't work correctly anyway.

How to test Luaj?

Andrew K. — Thu, 18 Jun 2015 23:32:58 -0000

I have downloaded the luaj-vm code from CVS and I'm trying to run the unit tests, but I cannot get them to execute.

If I run ant with no arguments it builds the jars without issue (apart from a few deprecation warnings).

However, if I run:
ant -buildfile build-coverage.xml
I get the following failure message:

andrew@ubuntu-VirtualBox:~/cvs/luaj/luaj-vm$ ant -buildfile build-coverage.xml
Buildfile: /home/andrew/cvs/luaj/luaj-vm/build-coverage.xml

BUILD FAILED
/home/andrew/cvs/luaj/luaj-vm/build-coverage.xml:15: Problem: failed to create task or type antlib:org.apache.maven.artifact.ant:dependencies
Cause: The name is undefined.
Action: Check the spelling.
Action: Check that any custom tasks/types have been declared.
Action: Check that any <presetdef>/<macrodef> declarations have taken place.
No types or tasks have been defined in this namespace yet

This appears to be an antlib declaration.
Action: Check that the implementing library exists in one of:
-/usr/share/ant/lib
-/home/andrew/.ant/lib
-a directory added on the command line with the -lib argument

Total time: 0 seconds

Line 15 refers to cobertura. I see the note about cobertura in the readme, but I'm not sure if I need to install it manually (or how to do so).

I'm new to ant, so I'm probably doing something wrong. Any help?

OS: Ubuntu 14.04 LTS (desktop, 64-bit) VM.
JDK: 1.8.0_45
Ant: 1.9.3
Maven: 3.0.5

Any possibilities to get lua call trace?

Lukas Jonyla — Sun, 03 May 2015 21:08:58 -0000

*tail calls are not tracked in debug information

It's really hard to find the culprit whenever some function fails(for e.g. rejecting nil argument)
Since the optional 'level' argument of error() doesn't have any effect, are there any ways(instead of hacky manual tracing) to get the lines of faulty function calls?

No more non-speaking "Attempt to call nil" messages :)

Stefan Reich — Sun, 22 Mar 2015 16:16:20 -0000

Another little idea for LuaJ that I like a lot - "named nils". Don't
you hate those non-speaking "attempt to call nil" messages, too? =)

Add to Lua.java:

    /** disable for more speed */
    public static final boolean useNamedNil = true;

    public static LuaValue namedNil(LuaValue name) {
            return useNamedNil ? new NamedNil(name) : NIL;
    }

Create this class:

package org.luaj.vm2;

public class NamedNil extends LuaNil {
  public LuaValue name;

  public NamedNil(LuaValue name) {
    this.name = name;
  }
}

Change 2 functions in LuaTable:

    public LuaValue rawget( LuaValue key ) {
            if ( key.isinttype() ) {
                    int ikey = key.toint();
                    if ( ikey>0 && ikey<=array.length ) {
                            LuaValue v = m_metatable == null
                                            ? array[ikey-1] : m_metatable.arrayget(array, ikey-1);
                            return v != null ? v : Lua.namedNil(key);
                    }
            }
            return hashget( key );
    }

    protected LuaValue hashget(LuaValue key) {
            if ( hashEntries > 0 ) {
                    for ( Slot slot = hash[ hashSlot(key) ]; slot != null; slot = slot.rest() ) {
                            StrongSlot foundSlot;
                            if ( ( foundSlot = slot.find(key) ) != null ) {
                                    return foundSlot.value();
                            }
                    }
            }
            return Lua.namedNil(key);
    }

Change LuaValue.checkmetatag:

    protected LuaValue checkmetatag(LuaValue tag, String reason) {
            LuaValue h = this.metatag(tag);
            if ( h.isnil() ) {
                    String errorText = reason + typename();
                    if (this instanceof NamedNil)
                            errorText += " (" + ((NamedNil) this).name.tojstring() + ")";
                    throw new LuaError(errorText);
            }
            return h;
    }

And, voila, when running scripts with undefined functions (let's say
loadURL is undefined):

_, _, url = snippetText:find("(http://.*)")
create {type='nt', text=loadURL(url), title='Contents of '..url..'

for '..snippetID}

...you get very nice error messages like this:

org.luaj.vm2.LuaError: #546:2 attempt to call nil (loadURL)

Performance hit should be small when turned on - and zero when turned
off and HotSpot-optimized.

Cheers,
Stefan

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luajc loader with tomcat

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No more non-speaking "Attempt to call nil" messages :)

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Any possibilities to get lua call trace?

No more non-speaking "Attempt to call nil" messages :)