Re: [boost] [review] hash functions

From: Dave Harris (brangdon_at_[hidden])
Date: 2005-03-09 14:32:12

In-Reply-To: <d0kr8r$gl6$1_at_[hidden]>
nesotto_at_[hidden] (Thorsten Ottosen) wrote (abridged):
> It's a pleasure to announce that the review of Daniel James' hash 
> functions library starts today (8th of March) and ends the 12th
> of March.

I have some questions about the design.

First, why does hash_combine have a void result, and have side-effects on 
its arguments? Wouldn't a pure, side-effect free function be better?

Second, why doesn't hash_range depend on the length of the sequence? For 
example, the hash_range of { 12 } and { 0, 0, 0, 12 } are the same. I'd 
rather they gave different results.

Thirdly, the hash values love producing 0. For example, hash_value( (char 
*) NULL ) and hash_value( false ) are both 0. hash_combine on a range of 
0s will produce another 0. Am I the only person who sees this as a 
problem?

-- Dave Harris, Nottingham, UK