Giovanni Piero Deretta wrote:
On Nov 8, 2007 2:19 AM, Yingwei Zhang <ywz@powerset.com> wrote:
Hello -
I am migrating our code base from boost 1.33.1 to 1.34.1. Some changes in boost/functional is causing compilation issues. The hash.hpp in 1.33 does include std container header files. In 1.34.1, however, forward declaration is added as following:
If you need the container headers you should include them, not rely on a third party header including it. In fact in this case conatainer_fwd IMHO does exactly the right thing. It forwards declare std containers when he thinks it is safe to do so. If It can't it includes them. Forward declaring standard containers without including the headers is something that comes handy very often.
That's exactly the reasoning. There was a fair amount of demand for this change. And I this is the first time anyone has been against it (and it's quite a long time since it was introduced). It's also worth noting that if in the future you used the standard C++ <functional> header instead you'd need to include the container headers as well. Unfortunately, the error messages are often confusing. Also, code that works on some platforms won't work on others - this also applies to the standard headers. I think this is part of the C++ condition. Daniel