Re: Guile and C++

[David Fang]

> > How would this work if I wanted to not run Guile embedded in a C++
> > program, but instead load the C++ code at runtime from a regular Guile
> > interpreter? (This could use either the libffi binding or the regular
> > Guile ones.)
>
> Since Guile is written in C, formally according to the C++ standard, you can 
> only load Guile from C++ code, and not the opposite. So main() must be C++.
>
> GCC though has integrated C and C++ fully, it seems. So you can call C++ from 
> C code, but the latter do not implement C++ exception stacks, and may not 
> call C++ initialization function properly (I haven't checked). It means that 
> throwing and catching exceptions within C++ functions called from C seems to 
> work fine, but if one tries to pass it through a C function, the program will 
> throw a terminate exception.

Hi,
	FWIW, I've used guile with C++ both ways: calling the main REPL 
loop in libguile from a C++ main, and also by creating loadable modules in 
C++, and calling load-extension with an initialization function.  Both 
work just fine, but you should be aware that guile errors do not unwind 
the stack on error, so C++ stack objects do not get destroyed in the event 
of exceptions/errors in the guile library.  I usually write the 
initialization function in the extern "C" namespace to avoid symbol name 
mangilng.
	Also, global statics in C++ modules are initialized upon 
loading, from what I've seen.

Fang


David Fang
http://www.csl.cornell.edu/~fang/
http://www.achronix.com/