----- Original Message ----- From: "Larry Evans" <cppljevans@cox-internet.com> To: <boost@lists.boost.org> Sent: Wednesday, August 10, 2005 12:10 PM Subject: Re: [boost] alignment problem in proposed any alternative
On 08/10/2005 09:27 AM, christopher diggins wrote: [snip]
Anyway it turns out we can guarantee alignment by simply using a char buffer. According to 3.9/2 the following automatically has no alignment problems:
template<int buffer_size> struct any { char buffer[buffer_size]; ... template<typename T> any(const T& x) { if (boost::is_pod<T>::value && (sizeof(T) <= buffer_size)) { memcpy(buffer, &T, N); Wouldn't this fail to update the refcount if T was shared_ptr or weak_ptr?
You are correct, but they aren't POD types so we would be safe. I can't help but wonder if this doesn't somehow imply placement new will work just as well. if ((sizeof(T) <= buffer_size)) { new(buffer) T(x); By the way, I made a small mistake originally it should have been memcpy(buffer, &x, N); Christopher Diggins http://www.cdiggins.com