Re: Future of g-wrap (and guile wrappers in general).

[Matthew]

I'm very much a newbie in terms of both Guile and interlanguage 
bindings, but I recently spent a few days working with g-wrap, SWIG and 
the libguile API to add scheme support to an application, and perhaps 
could add a few thoughts.

<snip>
> THE QUESTIONS:
>
> So the first question I'd like to ask is does Guile need a wrapper
> generator at all?
<snip>

Working directly with the "scm_/gh_" functions was very time consuming 
and repetative. I had about 80 functions or so that I wanted to wrap - 
in the end I just stopped bothering with things like type-checking, and 
eventually, the idea of using Guile to script my application ;-) Well, 
not quite. A wrapper generator would encourage the use of Guile in 
places where it might not otherwise be worth the effort.

Next (actually, this was all very much in parallel) I tried to work with 
g-wrap, because I had it installed, and because Gnucash uses it. I had a 
few problems with this; firstly, I found it difficult to understand how 
the wrapper specification worked [possible reason: the documentation is 
incomplete, or more likely, I'm just not too bright :) ]. Once I had 
this figured out, it was still quite time consuming to specify the 
functions and types. The third concern I had was that it needed a g-wrap 
runtime library, and I didn't want to add dependancies to my 
application. It was obvious that g-wrap provided fine control over how 
the wrappers and types were created, but _most_ of the time, I didn't 
need it.

> Another possibility would be to consider dropping guile in favor of
> SWIG and just working to make sure Guile's SWIG support is
> sophisticated enough to provide a really good solution.

Trying SWIG alleviated most of my problems - writing the interface file 
involved quite literally copying and pasting sections of my app header 
files. It automatically created accessor functions for my structs, which 
saved effort. The generated code was independant of SWIG, so users 
didn't need another dependancy. [Also, should I ever want it, I can 
trivially create Perl, Eiffel, Ruby, Java and, hmm, Tcl bindings]

> (though I don't think
> Guile is listed on their web page).

It is mentioned at least twice at http://www.swig.org . It's not 
anywhere near as heavily documented as the Perl, Tcl and Python stuff 
though :(

To, er, wrap up, I'd love to see work done to make SWIG work better with 
Guile (for one, the generated code compiles with pages of warnings!) 
rather than have to choose between close Guile control (g-wrap) and 
sheer ease of use (SWIG),

Matthew R.