Re: Automatic Qt bindings for Lua

["Mauro Iazzi" <mauro.iazzi@...>]

On 11/09/2007, Ariel Manzur <puntob@gmail.com> wrote:
> On 9/10/07, Mauro Iazzi <mauro.iazzi@gmail.com> wrote:
> > Given that much has changed between 4.1 and 4.3, I did not assume it
> > could work. The fact is that it is done with tolua++ which is a great
> > tool, if you control the source to be bound or it is quite small.
> >
> > The fact is that it requires some files (pkg) which must describe the
> > library code to tolua++. I don't know how those files were obtained
> > for Qt 4.1. but (miracles aside) they will not work with Qt 4.3.
> > Chances are that they were tweaked by hand (I _really_ don't know) and
> > seem not mantained anymore.
>
> As far as I know, the latest code on the SVN does compile with qt4.3
> (tested with qt-x11-opensource-src-4.3.0 aparently). Of course the
> bulk of the interface is not hand-tweaked (it was something like 15000
> methods for the whole thing), but some tweaking is needed to add
> convenient things (like transparent qvariants, stuff like that).
> But yeah, the API I have is pretty old..

wonderful, thanks for all the information.

I didn't really think that Qt API was so consistent between 4.1 and
4.3. It's very good that it works with 4.3.

I knew that those files weren't generated by hand. They were indeed a lot :)
I just didn't know the amount of hand work involved in generating
them. It could range from zero to a big amount. The nearest to zero,
the easiest to regenerate them in case of API break from Qt.

>
> > My code uses gccxml, which is a backend (frontend) of gcc which
> > exposes the internal gcc representation of the code as an XML tree.
>
> how much does the parser depend on the 'Expat' library you mention on
> the original mail? can it be done using one of the 'pure-lua' parsers
> available out there?

it depends just on having the tree structure similar to what luaexpat
does. It seemed quite a standard choice, looking in the wiki.

the code using it is actually:

  if not self.tree then
    local xmlf = io.open(filename, 'r')
    local xmls = xmlf:read('*a')
    xmlf:close()
    self.tree = lxp.lom.parse(xmls)
  end

then every other function uses that tree. I think that it would not be
hard to put any other parser in place of expat, given some
restructuring of the tree into the same format as luaexpat. Speed
could suffer, but I don't care for now.
If you have a better suggestion, I'll be glad to hear it. Pure-lua
parsers would eliminate a requirement, so are welcome.

I actualy thought It would be fine to produce automatically the pkgs
for tolua++, but I did not want to add another layer to the process.
My (badly named) common_bind.?pp files have probably the same
functions of the standard tolua++ headers, and probably duplicate much
of the functionality. Even if I didn't want to use tolua++, I could
have used those for common functions, but that wasn't so much work...

So, thanks again for the explainations above and I hope I've answered
to your questions,

mauro

>
> Ariel.
>
> > Then my generator processes it and makes the bindings. Ideally, if I
> > update to Qt 4.4, I just have to run it again. It would be a forever
> > up to date binding. I think it was worth trying whether it was
> > feasible.
> >
> > I'm quite happy of the results. They are almost usable for basic needs.
> >
> > mauro
> >
> > On 10/09/2007, Carlos Augusto Teixeira Mendes <cmendes@k2sistemas.com.br> wrote:
> > > Have you checked LuaQt by Ariel Manzur?
> > >
> > > It's pretty complete and works well.  Don't know if it has been updated
> > > recently. The version we are using is for Qt 4.1.x (latest version is
> > > 4.3.x).  Beside some small corrections it worked fine for us.
> > >
> > > cheers,
> > > Carlos Augusto.
> > >
> > > > -----Original Message-----
> > > > From: lua-bounces@bazar2.conectiva.com.br
> > > > [mailto:lua-bounces@bazar2.conectiva.com.br]On Behalf Of Mauro Iazzi
> > > > Sent: Saturday, September 08, 2007 2:46 PM
> > > > To: lua@bazar2.conectiva.com.br
> > > > Subject: Automatic Qt bindings for Lua
> > > >
> > > >
> > > > Hi all,
> > > >
> > > > in the past months I used some of my spare time to make Qt bindings
> > > > for Lua. I now have a working simple program to show how far I've got,
> > > > and a little screencast showing off some capabilities.
> > > >
> > > > The program is here:
> > > > http://linuz.sns.it/~iazzi/lqtutorial.tar.gz
> > > >
> > > > The screencast is here:
> > > > http://linuz.sns.it/~iazzi/tutorial.ogg
> > > >
> > > > To compile use
> > > > qmake
> > > > make
> > > > ./lqtutorial
> > > >
> > > > Users of Debian-based systems should be fine using the
> > > > lqtutorial.pro.debian file.
> > > >
> > > > The bindings are autogenerated using the output ogf GCCXML. I included
> > > > the bindings for just a few basic classes. I will try and package the
> > > > generator in a few days. The generator is written in less than 1000
> > > > lines of Lua code, and makes use of the Expat library for parsing XML.
> > > >
> > > > Among the best hings there is the fact that I did not have to touch
> > > > any generated file by hand. They just worked.
> > > >
> > > > Moreover, they are completely modular, so that I can have the bindings
> > > > for only few classes that I actually need. This provides a lot of
> > > > modularity, which could be exploited to make very small programs.
> > > >
> > > > Finally, the generator has only be used on Qt, but is totally generic,
> > > > and can be used on any C++ code, although I don't know how well it
> > > > would understand some complex features of C++ (as deeply nested local
> > > > classes, barbaric use of templates and such).
> > > >
> > > > I strongly hope that this is of some interest to someone.
> > > > Cheers,
> > > >
> > > > mauro
> > > > No virus found in this incoming message.
> > > > Checked by AVG.
> > > > Version: 7.5.485 / Virus Database: 269.13.13/998 - Release Date:
> > > > 9/10/2007 8:48 AM
> > > >
> > > No virus found in this outgoing message.
> > > Checked by AVG.
> > > Version: 7.5.485 / Virus Database: 269.13.13/998 - Release Date: 9/10/2007
> > > 8:48 AM
> > >
> > >
> >
>