Hi Larry,
[snip] The attached demonstrates, I believe, what Thorsten was aiming at an shows the storage of *different* types in contiguous storage.
I was hoping this could be done a lot easier. My outset is that objects are added by saying // in-place contruction by forwarding x and y cont.push_back<Derived>( x, y ); This should give maximum information about the size and alignment of Derived to the container, allthough I was hoping that some kind of maximal aligment could be assumed, eg. 4 bytes boundaries on 32 bit systems. I see no limitation in adding the elements this way, as it completely mirrors a container of pointers: ptr_container.push_back( new Derived( x, y ) ); So far so good. The polymorphic_vector< class Base, class Allocator > class template would internally only need an std::vector<char>. The question would be how to copy the objects? This is where I imagined the base class requirement should enter, that is, the base class of the class hierarchy should inherit from boost::polymophic_object which has a single function: unsigned copy( char* into, const char* from ) { // inplace copy or move return sizeof(Derived); } In any case, I would rather see virtual functions to be added to this interface if it removes the need to store things like size/alignment. When saying // in-place contruction by forwarding x and y cont.push_back<Derived>( x, y ); we should also store a pointer to the next element to allow forward iteration, so maybe a start and end pointer also needs to be stored directly in the container. Perhaps this can be avoided by just letting the user get a pointer from push_back. -Thorsten