On Wed, May 13, 2009 at 8:49 AM, Stewart, Robert <Robert.Stewart@sig.com> wrote:
Beman Dawes wrote:
...
The problem with waiting for a header to be totally complete means waiting a long time. For example, several vendors are already, or will soon be, shipping a number of new C++0x headers. But their implementations aren't "complete" because they don't have concepts yet. The headers are perfectly usable, however, so there is no reason not to take advantage of them now. For some of these compilers we many have to wait several years before concepts become available, and the headers become "complete".
Yes, concepts are unique in coming very late to the party. I agree with your idea, so long as the header macros don't indicate a header is present with any other deficiency or the logic to determine if needed functionality is present will get complicated.
We are definitely feeling our way here. Also, it isn't an easy task to determine if a header has other deficiencies. Unless someone objects strenuously, I'll go ahead and add the proposed header macros knowing full well that still others with finer granularity may be needed. Also, some features go in existing headers, so the macro might have to be something like BOOST_NO_CPP0X_UTILITY_HDR. I'll try to add appropriate macros for at least a few of the more critical of those. --Beman