On Feb 11, 2006, at 2:16 PM, Kim Barrett wrote:
At 11:52 AM -0800 2/11/06, Robert Ramey wrote:
David Abrahams wrote:
IMO the size_type change should be considered a bugfix, as it was not possible to portably serialize collections
of over 4 G objects
Strictly speaking, of any size. And changing the type of the count from "unsigned int" to std::size_t would actually be worse, in a practical sense. The representation size (how many bits of data will appear in the archive) must be the same on all platforms.
sizeof(unsigned int) is commonly 4 on 32bit platforms sizeof(unsigned int) is (I think) commonly 4 on 64bit platforms
no, it can be 4 or 8 depending on the platform
sizeof(std::size_t) is commonly 4 on 32bit platforms sizeof(std::size_t) is commonly 8 on 64bit platforms
(I'm knowingly and intentionally ignoring DSP's and the like in the above).
The count should be some type that has a fixed (up to byte-order issues) representation, i.e. something like uint64_t.
Or one can leave it up to the archive to decide how to store the count. That's why I proposed to introduce a collection_size_type object storing the count. Any archive can then decide for itself how to serialize it, whether as unsigned int, uint64_t or whatever you like. Matthias