A generic solution (cont'd)

 1   VALUE foo(VALUE self, VALUE x) {
 2     RUBY_TRY {
 3       Foo f;
 4       f.foo(CPP_NUM2INT(x));
 5       return Qnil;
 6     } catch(std::bad_alloc & ex) {
 7       RUBY_RETHROW(rb_exc_new2(
 8           rb_eRuntimeError,
 9           "failed to allocate memory"));
10     } RUBY_CATCH
11   }