[boost] Re: [boost.tr1?] request for a hash<> implementation

From: Daniel James (daniel_at_[hidden])
Date: 2005-02-07 07:25:47

JOAQUIN LOPEZ MU?Z wrote:
> You've been fast! I've taken a look at your stuff and have
> a couple of concerns/suggestions:

Not that fast, most of the implementation is just copied out of Peter's 
specs.

By the way, don't put much trust into the hashes for floats yet. I 
should have mentioned that before. I'll write more tests for them before 
you release anything properly.

> 1. Now the file is boost/hash/functional.hpp. Wouldn't it
> be better to call it boost/functional/hash.hpp? As I see it, hash<>
> is part of TR1 future <functional>, so the naming
> I propose looks more consistent.

Yeah, I'll do that. Although, until it's formally a part of boost, I 
thought you'd just be putting it into a detail directory.

> 2. The header includes <set> and <map>, which can be quite heavy
> if the user has no intention to use the corresponding hash_value
> overloads. Alas, I don't know of any way to avoid the inclusions,
> since a forward declaration of these containers can fail due
> to the freedom stdlib implementers have to add additional template
> parameters to those specified by the standard. Any idea?

The only thing I can think of is seperating the file into two different 
headers, something like boost/functional/hash.hpp and 
boost/functional/hash_containers.hpp. But that would be pretty awkward 
to use.

Daniel