On 09/17/2010 08:37 AM, dherring@ll.mit.edu wrote:
On Fri, 17 Sep 2010, Steven Watanabe wrote:
dherring@ll.mit.edu wrote:
While C++0x promises to change things (see draft spec section 9.5), C++ currently does not allow unions to contain members having a nontrivial constructor, operator=, or destructor. This excludes std::string, std::complex, structures containing either, etc.
The "standard" workaround is to allocate your own memory and use manual type casting. Boost::aligned_storage can be used to maintain proper alignment, but it cannot be placed inside a union due to the default ctor, dtor, and noncopyable functions. Thus I am forced to use part of boost::detail.
Use boost::aligned_storage<...>::type which should be POD.
Thanks. Missed that typedef to the detail. Any other comments on the approach would be appreciated.
- Daniel
You can also use boost::type_with_alignment<N>::type within a union to force a particular alignment. - Jeff