From: Simon Strandgaard <0bz63fz3m1qt3001@...>
Date: 2003-05-15T00:03:31+09:00
Subject: Re: ruby_run() w/o exit?

On Wed, 14 May 2003 15:31:14 +0000, ahoward wrote:
> i peeked through ruby.h a little, and of course the pickaxe, but there does
> not seem to be a function similar to ruby_run() which does not cause the
> calling process to exit().  of course, one can use rb_eval_string(), etc...
> 
> what would the best way to repeatedly call the interpreter?  

rb_funcall().. does *most* of what you want. 
You will have to wrap rb_funcall into a rb_protect() call in order 
to catch all exceptions. I you don't use rb_protect and an error occurs
within your ruby code your application will be exit'ed.


/* ------------------------------
wrap rb_funcall
------------------------------ */
struct Arguments {
    VALUE recv;
    ID id;
    int n;
    VALUE *argv;
    Arguments(VALUE recv, ID id, int n, VALUE *argv) :
        recv(recv), id(id), n(n), argv(argv) {
    }
};

VALUE FuncallWrap(VALUE arg) {
    Arguments &a = *reinterpret_cast<Arguments*>(arg);
    return rb_funcall2(a.recv, a.id, a.n, a.argv);
}

/*
purpose:
call a ruby function in a safe way. 
translate ruby errors into c++ exceptions.
*/
VALUE Funcall(VALUE recv, ID id, int n, ...) {
    VALUE *argv = 0;

    if(n > 0) {
        argv = ALLOCA_N(VALUE, n);
        va_list ar;
        va_start(ar, n);
        int i;
        for(i=0;i<n;i++) {
            argv[i] = va_arg(ar, VALUE);
        }
        va_end(ar);
    } 

    Arguments arg(recv, id, n, argv);
    int error = 0;
    VALUE result = rb_protect(FuncallWrap, reinterpret_cast<VALUE>(&arg), &error);
    if(error) {
        //throw RubyError::Create("cannot invoke ruby-function");
        throw;
    }
    return result;
} 




VALUE Safe() {
    return Funcall(
        self, 
        rb_intern("my_super_nice_test_function_in_ruby"), 
        1, 
        INT2NUM(42)
    );
}



See the turorial for furhter info:
http://metaeditor.sourceforge.net/embed/index.html


--
Simon Strandgaard