Hi! I'd like to implement a pimpl, pointing to a stack "allocated" buffer by means of palcement new/destroy. There would be no problem but there are alignment issues. What really I need is: - a way to check by te means of Boost wheater that an object of class X can be placed (with placement new) in a buffer of given adress and size: - a way of getting a pointer to X (within the buffer) where the object could be paced // file.hpp: struct X { X(); ~X(); private: struct Impl; const static int max_size = 100; Impl* m_pimpl; char m_impl_buffer[max_size]; bool m_on_stack; }; // file.cpp: #include "file.hpp" struct X::Impl { // members }; X::X() { m_on_stack = value_of(max_size is big enough for an object of X); if (m_on_stack) m_pimpl = new (m_impl_buffer)Impl; // any alignment stuff here??? else m_pimpl = new Impl; } X::~X() { if (m_on_stack) m_pimpl->~Impl(); else delete m_pimpl; } I'll be gratefull for any help, Michal