From: Daniel Harple <dharple@...>
Date: 2006-08-09T05:32:34+09:00
Subject: Using C++ Member Function with rb_protect

I'm having problems using a C++ member function with rb_protect. Here  
is the code:

class Sandbox {
public:
     Sandbox() {
         sandbox_ = rb_funcall(rb_const_get(rb_cObject, rb_intern 
("Sandbox")),
                               rb_intern("safe"),
                               0);
     }
     virtual ~Sandbox() {
     }
     VALUE eval(char * code) {
         int status = 0;
         VALUE val = rb_protect(&Sandbox::eval_protect,
                                rb_str_new2(code),
                                &status);
         if (status) { /* handle error... */ }
         return val;
     }
private:
     VALUE eval_protect(VALUE code) {
         return rb_funcall(sandbox_, rb_intern("eval"), 1, code);
     }
     VALUE sandbox_;
};

The compile fails with:

test.cpp: In member function �VALUE Sandbox::eval(char*)�:
test.cpp:18: error: cannot convert �VALUE (Sandbox::*)(VALUE)� to  
�VALUE (*)(VALUE)� for argument �1� to �VALUE rb_protect(VALUE (*) 
(VALUE), VALUE, int*)�

$ ruby1.8 -v
ruby 1.8.5 (2006-08-06) [powerpc-darwin8.7.0]
$ g++ --version
powerpc-apple-darwin8-g++-4.0.1 (GCC) 4.0.1 (Apple Computer, Inc.  
build 5341)
Copyright (C) 2005 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There  
is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR  
PURPOSE.

Any ideas?

Thanks,
-- Daniel