Re: Mochalua - Lua for J2ME

["Kristofer Karlsson" <kristofer.karlsson@...>]

Hi, I am the author or Kahlua.
This is a very interesting project, and I will take a deeper look at
it later (I am at work right now).
>From what I can tell, the main differences between Kahlua and Mochalua are:

1) Mochalua is intended to be a full port of Lua, as close to the
original as possible, whereas Kahlua is intended to be a minimal
reimplementation of the Lua Virtual Machine. Kahlua also tries to
emulate all the base library as much as is reasonable without adding
too much bloat.

2) Kahlua is intended to be as small as possible, for distribution on
mobile devices. The jar file produced by Kahlua is 50KB and the one
you can download from Mochalua is 287KB. A more interesting figure
might be how large they are after obfuscation, but I haven't done that
comparison yet.

3) Kahlua has a goal of keeping the source code light. Total lines of
code is 4805 in Kahlua and 16951 in Mochalua.

4) Kahlua has a goal of keeping the number of classes light. I used
this simple tool to measure it: rgrep " class " *|grep -v svn|wc
Kahlua has 15 and Mochalua has 208.

5) Kahlua has a goal of reusing as much as possible from the Java
world - for instance, Kahlua doesn't implement any garbage collection
of its own, which means it can't provide utility hooks such as __gc. I
have not delved into the details of Mochalua, but if it provides __gc,
it seems like it should have to perform some garbage collection
manually. Is this a reasonable guess? :-)

6) Integration with Kahlua is different compared to how you do it from
C. I personally think it's easier in Kahlua, since you get immediate
access to all objects in Lua space. In fact, the distinction between
Lua space and C/Java space is barely there at all in Kahlua. Mochalua
has probably the benefit of being easier to work with for people who
are used to the behaviour of using Lua with C.

As a note, Kahlua does have support for Coroutines these days, and
they seem to work quite well, I'm happy to say! :-)

As I said, I'll take a closer look later, but Mochalua indeed looks interesting!

/Kristofer

On Tue, Nov 18, 2008 at 3:58 AM, Patrick Meehan <patrick@groundspeak.com> wrote:
> There's a .jar up now for anyone interested.
>
> Re differences from the current version of Kahlua, I couldn't say.  When we first looked at what was out there it seemed like the implementation of Kahlua was pretty preliminary - the author was still thinking about how to do things like coroutines.  It looked like (as I recall) just the basic LVM.  I don't think it implemented much of the Lua API.
>
> We commissioned Mochalua so we could port a mature C language code base we use internally, so the focus was on being fully featured.  It is intended to be an exhaustive port of everything but the compiler.  It's (slavishly) true to the C API - you should be able to just cut and paste your C language glue code, prefix it with the API classname and have it work.  We've ported (almost) the entire API, Lua libraries, debug libraries and LVM functionality (coroutines, etc.).  We even trap userdata going out of scope and call the __gc metamethod.  Mochalua also reports the standard Lua runtime errors with file name and line number in the same format as the C version.
>
> Kahlua may have come a long way since we looked at earlier this year; once we committed to doing our own port, we didn't look back.
>
> Anyway, at the very least Mochalua is another Lua implementation for people to consider.  I should also mention that it includes a J2ME port of a lot of the C standard libraries to support the Lua libraries - math.h, printf, etc.  It was written for J2ME, but can certainly be retargetted for any Java project - there should be nothing inside of the Mochalua source that requires or expects a Midlet to run.
>
> -----Original Message-----
> From: lua-bounces@bazar2.conectiva.com.br [mailto:lua-bounces@bazar2.conectiva.com.br] On Behalf Of David Manura
> Sent: Monday, November 17, 2008 5:48 PM
> To: lua@bazar2.conectiva.com.br
> Subject: Re: Mochalua - Lua for J2ME
>
>> On Mon, Nov 17, 2008 at 4:42 PM, Patrick Meehan wrote:
>> > I'd like to announce the release of Mochalua, a J2ME port of the Lua
>> > runtime and API, as open source under the MIT license.
>
> This is now on the Lua Implementations page[1], but could you elaborate on the differences between Mochalua[2] and Kahlua[3]?
>
> [1] http://lua-users.org/wiki/LuaImplementations
> [2] http://code.google.com/p/mochalua/
> [3] http://code.google.com/p/kahlua/
>
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