On Sun, 7 Mar 2004 15:44:22 -0800, "Robert Ramey" <ramey@rrsd.com> wrote:
Robert Ramey wrote:
This exchange illustrates the problem rather nicely. Its not clear to me from the name "aligned_storage" that its meant to do the same job as "stack_allocate" and in fact is easily confused with other boost functions. I've been able to find no documentation nor test nor other information. The only place its used is in variant.hpp but its not mentioned in the documentation of that either. There is no statement in the header itself as to what it does and the code is sufficiently non-trivial that it's not obvious what its supposed to do. The fact that it has a parameter than stack_allocate doesn't need also suggests that it's intended purpose is different from that of stack_allocate.
The previous post referred to alignment_of rather than aligned_storage which seems to me to unrelated. Are they related in some non-obvious (to me) way?
aligned_storage can be (and in fact is) implemented in terms of alignment_of and type_with_alignment. Even if you don't want to use aligned_storage, since it isn't a full part of boost yet (it didn't ship with the last release), you could use use type traits to implement your own correct stack_allocate function. e.g. template<class T> struct stack_allocate { union { char a[sizeof(T)]; type_with_alignment<alignment_of<T>::value>::type b; } mem; T * address(){ void * vptr = &mem; return static_cast<T *>(vptr); } T & reference(){ return * address(); } }; or something like that. Tom -- C++ FAQ: http://www.parashift.com/c++-faq-lite/ C FAQ: http://www.eskimo.com/~scs/C-faq/top.html