`as_container` looks interesting! Here are some comments on `as_container`: * `as_container_functor` and `operator |` live in different name spaces. So ADL does not work. * `as_container` should live in boost::adaptors? * Built-in arrays are not supported by `as_container`. * Template conversion operator ambiguity: In C++03 and C++11, the following code boost::array<int, 3> ar = {{1, 2, 3}}; std::vector<int> v(ar | as_container); fails to compile due to the ambiguity between - `explicit vector(const allocator_type&)`, - `vector(initializer_list<value_type>)`, and - `vector(const vector&)`. In C++11, the following code boost::array<int, 3> ar = {{1, 2, 3}}; std::vector<int> v; v = ar | as_container; fails to compile due to the ambiguity between - `vector& operator=(initializer_list<value_type>)`, and - `vector& operator=(const vector&)`. One solution to this problem is applying SFINAE by "default template arguments for function templates" to the template conversion operator: template < class Container , class Dummy1 = typename Container::difference_type , class Dummy2 = typename Container::iterator > operator Container() const { /* ... */ } (`Dummy1` is used to SFINAE out `std::initializer_list` and `Dummy2` is used to SFINAE out `std::allocator`.) But this is a C++11 feature and so ambiguity with `std::allocator` is not solved in C++03. If there is no simple solution, simply documenting the limitation is an acceptable solution, I think. Regards, Michel