newlisp and the C++ revolution

newdep · Post by **newdep** » Wed Jul 08, 2009 8:40 pm

It seems that more and more library's are moving towards c++
This hasnt been always the case. I know some pretty nice languages
that where c library based and also Gui's and other applications..

Somehow it all slightly is moving towards c++ and being a newlisp user
im wondering how to overcome the fact that newlisp cant keep up with
binding to library's.

Im far from a c++ programmer so i dont know the details but there
must be a way to interact with c++ library's somehow.. and it is
discussed befor here but not deep enough!

This topic is realy eating me as I have some nice projects on the stack
that get dusty because im not willing to learn c++ but want a binding
to a highlevel language..

Is there a way to adjust or add-on something/somehow to newlisp to
make c++ library binding happen...
Not only for mysake but for the sake of newlisp's future perhpas..

Just a mind storm that keeps me awake...

newdep · Post by **newdep** » Wed Jul 08, 2009 8:51 pm

How does Python do this?
I know that python can do c++ library's by the use of a language (c++?)
that transforms it back to python functions.. How its done i dont know
but this kind of interface is actualy a solution..

newdep · Post by **newdep** » Thu Jul 09, 2009 6:55 am

reading reading..reading..
The only way to do this is writing a wrap around the cpp lib.
And there is no way of doing this without the intervention of cpp.
This asks for creativity...and is btw a generic 'problem' of cpp.
case closed.. again..pitty..

Lutz · Post by **Lutz** » Thu Jul 09, 2009 11:38 am

For Python there are tools available to generate wrappers automatically, e.g. from: http://www.language-binding.net . Probably these could be adapted for newLISP too; but then it is probably quicker to write a wrapper yourself in 'C'. If one is doing a module anyway, this is not much of additional work.

xytroxon · Post by **xytroxon** » Thu Jul 09, 2009 4:53 pm

For a more generic method:

SWIG - (Simplified Wrapper and Interface Generator)
http://www.swig.org/

SWIG is an interface compiler that connects programs written in C and C++ with scripting languages such as Perl, Python, Ruby, and Tcl. It works by taking the declarations found in C/C++ header files and using them to generate the wrapper code that scripting languages need to access the underlying C/C++ code. In addition, SWIG provides a variety of customization features that let you tailor the wrapping process to suit your application.

-- xytroxon

itistoday · Post by **itistoday** » Wed Jul 15, 2009 1:45 am

Yes it would be cool if newLISP had this capability. I for one would like to use it with a project like Ogre3D, which is written in C++. Maybe someone will look into doing the SWIG for newLISP... damn, I wish I could clone myself (anyone seen Multiplicity?)..

Elica · Post by **Elica** » Wed Jul 15, 2009 6:19 pm

Just curious about C++ libraries which do use OOP within their APIs. How would one deal with stuff like this?

itistoday · Post by **itistoday** » Wed Jul 15, 2009 6:35 pm

Elica wrote:Just curious about C++ libraries which do use OOP within their APIs. How would one deal with stuff like this?

I would guess that you would somehow let C++ deal with that since newLISP can't do OOP like C++.

Something like this (warning, written on the whim):

Code: Select all

(set 'cppObj (MyCppClass::getInstance))
(MyCppClass::setName cppObj "Dog")

What's interesting is that MyCppClass becomes a context in newLISP, with a function called ":getInstance" and ":setName", where the former is a static function and the latter is a ... whatchamacallit, instance function?

Whether these functions would be mapped directly to their corresponding C++ methods, or through some sort of a trampoline function, I don't know.

itistoday · Post by **itistoday** » Wed Jul 15, 2009 6:43 pm

Then there's also the question of C++ namespaces and what to do about them. Because C++ can have namespaces within namespaces (I think), it may actually be a real pain to get newLISP to work with it really nicely like above.

You would probably have to have some sort of convention like they PyObjC wrapper, where special characters like the underscore are used. Thereby you would simply have symbols pointing directly to their corresponding C++ counterparts.

It would also be interesting to consider how to use newLISP contexts in this situation to get the best performance and usability out of such a system, as the number of symbols that could be imported from a large C++ project would be staggering...

newdep · Post by **newdep** » Mon Jul 20, 2009 3:58 pm

Actualy Im hitting this question because the Smartphone technology is
all based on C++. Porting newlisp to an ARM version isnt propably the
most difficult part but letting it interact with C++ is.

Btw.. Does someone have a SmartPhone here? With Symbian on it?
Python is already there... Perl is half way.. so time for newlisp to Run
on more then only Intel..i guess .. (I already kicked off with the ARMEL version ;-)

http://www.symbian.org/

PS: Btw... Intel is catching up in the Smartphone/handheld area..
Not quick but they are trying.. So Symbian does already run on the
Intel/Atom.

xytroxon · Post by **xytroxon** » Mon Jul 20, 2009 7:45 pm

You could always compile newLISP as C++... Change .c files to .cpp etc... But, then you get to debug it ;)

SWIG helps you with the C++ Class stuff... but to program it from newLISP, you still need to understand C++... A library like Ogre3D really needs to be run from C++ code to be fast... Even so, Python does have an interface you might look at:
http://en.wikipedia.org/wiki/Python-Ogre

But the major problem, is that C++ compiler "name mangling" of dll function names is not consistant... Visual C++ is different than MinGW is different than WatCom, Borland etc...

So to effectively use SWIG, the library and newLISP++ must be compiled with the same compiler brand...

And as Lutz has proven, Java is already useable from newLISP... And Java programming is "safer" than C++ programming... (LOL)

Also interfacing C librarys from C++ is very easy... But C++ libraries from C is very messy...

So retargeting newLISP to C++ may seem like a good idea, but C++ compiled code quickly expands in executable code size and that also reduces execution speed... All that object oriented functionality comes at a cost... And negating the newLISP size and speed advantage over other scripting languages...

So nothing is really as easy as it first seems... :)

-- xytroxon

pjot · Post by **pjot** » Tue Jul 21, 2009 9:26 pm

Well the answer maybe here:

http://www.isotton.com/devel/docs/C++-d ... HOWTO.html

It is a lot of work though, adding 'EXTERN C' to your relevant functions ;-)

Well crap, C++ is kind of a hype anyway. For small applications you're looking at, it's really useless. Do you know how many lines of code one needs for a simple 'Hello world' application in C++?

But if you're bound with your Nokia environment, it's a pain of course. I guess the only thing you can do is writing your own wrapper ;-)

Cheers
Peter

Elica · Post by **Elica** » Wed Jul 29, 2009 10:11 am

pjot wrote:Do you know how many lines of code one needs for a simple 'Hello world' application in C++?

The same number of lines as in C.

Code: Select all

#include <iostream>
 
int main()
{
    std::cout << "Hello, world!\n";
}

More examples including some funny languages are available in Transwiki:List of hello world programs

pjot · Post by **pjot** » Wed Jul 29, 2009 6:20 pm

OK. Now let's do the same in newLisp:

Code: Select all

(println "Hello, world!")

Looks less code to me... ;-)