Jonathan Wakely wrote:

http://boost.org/libs/smart_ptr/enable_shared_from_this.html says:

Requires: enable_shared_from_this<T> must be an accessible base class of T.

I've seen this - but even if I make the inheritance protected, VC++7.1 balks at it complaining that a conversion from the type T to enable_shared_from_this is available but inaccessible.

Obviously using public inheritance works, but you might also be able to make it work by making shared_ptr<T> a friend of policy<T> so it can do the conversion. You'll also need to disable the BOOST_ASSERTs in enable_shared_from_this.hpp by defining BOOST_DISABLE_ASSERTS or by copying enable_shared_from_this.hpp and re-implementing the class without the assertions. I have no idea if this is supposed to work, nor if it will still work if the internals of shared_ptr or enable_shared_from_this change. Caveat emptor.

I've tried friendship as you recommend, between shared_ptr<T> and policy<T>, but again without success. Interestingly, I actually get the error from a construction of a standard shared_ptr, without even using shared_from_this. I've gone as far as commenting out every call to shared_from_this in my code. If I inherit from enable_shared_from_this, the compiler complains on construction of a shared_ptr in the detail::sp_enable_shared_from_this line in the code below. If I also comment out enable_shared_from_this, everything compiles okay. template<class Y> explicit shared_ptr(Y * p): px(p), pn(p, checked_deleter<Y>()) // Y must be complete { detail::sp_enable_shared_from_this(p, p, pn); } This is remarkably frustrating, since there are a large number of implementation details in my policy class that I am keen to hide from the API, and the API works fine for all my other policies, it is just the shared_ptr policy that is collapsing. Dave