Re: [q-lang-users] windoze libraries question

[Albert G. <Dr....@t-...>]

Evan Hawkins wrote:
> What is the procedure to make these libraries "available" to Q?

Which libraries exactly? The Windows APIs are huge. :)

For moderately-sized APIs, there's Q's native C interface (see Appendix
C of the manual,
http://q-lang.sourceforge.net/qdoc/qdoc_15.html#SEC156). The biggest Q
module written using that to date is clib, Q's POSIX system interface,
you can find the sources of that in the Q source package,
http://prdownloads.sourceforge.net/q-lang/q-7.6.tar.gz?download

The direct C interface is probably easier to understand, but for bigger
libraries your best bet would be SWIG, because it generates most of the
necessary wrapper code for you. There's a Q-enabled SWIG version
available on the Q website (and a binary for Q-SWIG is already included
in the Qpad package):
http://prdownloads.sourceforge.net/q-lang/swig-1.3.22-q-20060225.tar.gz?download

Unfortunately, there's no specific Q-SWIG documentation yet (beyond the
generic SWIG 1.3.22 documentation). However, two basic examples can be
found in the Qpad/examples/swig folder, more examples are included in
the Q-SWIG source package (see the link above), and some of the modules
(e.g., Q's interfaces to OpenGL, SQLite etc.) are also written using
SWIG, so you can study the sources of those (all available at
http://q-lang.sourceforge.net/download.html#Sources) to see how to deal
with full-blown libraries. (But make sure to take a look at the basic
examples first. It's also instructive to look at the generated C/C++
wrapper code to better understand SWIG's inner workings. Essentially
it's all about marshalling Q data to C, running the C function, then
converting C/C++ results back to Q.)

For simple interfaces it's often just a matter of writing a minimal SWIG
interface (.i) file which either pulls in the necessary C/C++ header
files or just declares the prototypes of the required functions. Q-SWIG
already "knows" about simple C data types like numbers and strings and
generic pointers, but if you need to wrap elaborate data structures,
you'll probably need to supply your own "typemaps" to tell SWIG how to
deal with them. The most complex issues arise if your C/C++ code needs
to call back into Q, but this can be done, too, if done properly (you
can find examples of this, e.g., in the OpenGL and SQLite modules).

HTH,
Albert

-- 
Dr. Albert Gr"af
Dept. of Music-Informatics, University of Mainz, Germany
Email:  Dr....@t-..., ag...@mu...
WWW:    http://www.musikinformatik.uni-mainz.de/ag