David Abrahams wrote:
I've developed some facilities that perhaps ought to be developed into full-fledged libraries or components of existing Boost libraries. This work centers around my long-standing threat to build a library that could create smart pointers safely, without ever exposing a raw pointer to the user. For example,
#include <memory> #include <boost/shared_ptr.hpp> #include "new.hpp"
struct foo { foo(int&, char const*, std::auto_ptr<int> const&); };
std::auto_ptr<int> x(new_<int>(3)); std::auto_ptr<foo> y(new_<foo>(*x, "hello, world", x)); boost::shared_ptr<foo> z(new_<foo>(*x, (char const*)"hello, world", x));
To solve this problem correctly, it was necessary to address "the forwarding problem" (http://std.dkuug.dk/jtc1/sc22/wg21/docs/papers/2002/n1385.htm). To that end, I developed some preprocessor macros that one can use to generate the necessary overload sets. Is there interest in adopting any of this code (enclosed), and if so, where should it go?
First, I'd like to say that I am very interested in this in a general way, as I frequently end up writing forwarding sets (although usually escape the forwarding problem). I'm not intimate with the pp library, but if I read your code correctly you have "solved the forwarding problem" by writing all the permutations of const and non const for each forwarding set. Is that correct? If not could you clarify for us non-PPers? Personally I don't like the "new_" name. but that's purely subjective. I think I'd prefer something more like, "atomic_new" (although that could also be a bit misleading), or that at least has something more descriptive to indicate what else is going on, other than just a bare trailing _. What about the array form? Would it be worth going as far as to add static functions to the boost smart pointer classes that do the same thing, and even hidding their raw pointer constructors away so they can only be created using the safer factory methods? Obviously that last step would break existing code, but it would only break the largely unsafe uses. Best regards, [)o IhIL..