Hi Daniel, Daniel James ha escrito:
Joaquín Mª López Muñoz wrote:
Comments on the implementation.
1. The overloads of hash_value for STL containers forces the implementation to include <vector>, <list>, etc., which makes the header a little heavier than desired. Of course, this could be avoided if only there exist <vector_fwd> style headers :( I propose that, instead of including the STL containers headers, they are forward declared:
namespace std{ template<typenameT,typename A> class std::vector<T, A>; .... }
As is known, stdlib implementors are free to add extra template params, so this is not 100% safe, but: * All stdlibs that I'm aware of do not include extra template params * The forward declarations can be tweaked for those stdlibs for which they don't match.
I'm not happy with this either.
Why not? Sure it has the overhead of checking validity against every new stdlib that comes around, but you've already commited to this kind of activity with the workarounds on float_functions.hpp Besides, the amount of work needed to accommodate a new library is 0 in most cases and negligible in the rare cases where extra template parms are used.
Another possible solution is to just use Boost.Range on anything that 'looks' like a container. But this will break on unordered containers (as equivalent containers can have different sequences).
Too broad IMHO.
2. It is said in hash.cpp that BCB has problems with the overload of hash_value for bool. This should be fixed in one way or another (possibly by not defining it for this compiler, I guess.)
It actually says that BCB has problems without it. There was an overload ambiguity error for boost::hash<bool> (although, calling boost::hash<bool> would be a very odd thing to do) and that was added to work around it.
Oh, sorry, I misread it. I agree with you hashing a bool makes little sense, and agree that it probably shouldn't be made part of the public interface (for the same reasons, for instance, that there's no overload for char.) Joaquín M López Muñoz Telefónica, Investigación y Desarrollo