General design question here. This came up on the user's list, and it made me question something I believed to be true. When writing a proxy for, e.g., a std container, I see two options for handling const. 0) Const-ness depends on the const-ness of the object being proxied: struct vector_proxy { std::vector<int> & vec; typedef std::vector<int>::iterator iterator; typedef std::vector<int>::iterator const_iterator; iterator begin() const { return vec.begin(); } ... }; 1) Const-ness depends on the proxy object itself: struct vector_proxy { std::vector<int> & vec; typedef std::vector<int>::iterator iterator; typedef std::vector<int>::const_iterator const_iterator; iterator begin() { return vec.begin(); } const_iterator begin() const { return vec.begin(); } ... }; I think a loooong time ago, I preferred (1) but these days (0) is more natural for me, but I can't say why, exactly. Just feels like that's how it should be. Thoughts? FWIW, it came up in the context of BOOST_FOREACH's handling of proxies, so it's not (far) off-topic. -- Eric Niebler Boost Consulting www.boost-consulting.com The Astoria Seminar ==> http://www.astoriaseminar.com