Re: [Boost-users] [review] Review of Unordered library begins today December 7

From: Ion Gaztañaga (igaztanaga_at_[hidden])
Date: 2007-12-08 19:42:52

gchen wrote:
> What is the difference of this library from hash_map in some STL 
> extention libraries?
> Is it just a new name for hash_map/hash_set?

Hash containers were not standardized so there are different 
implementations with different guarantees and features (some used 
incremental hashing or bidirectional iterators) and C++ unordered 
containers have been standardized to support a broad range of 
implementations adding new features, like bucket iterators.

You shouldn't use hash_map and other similar containers if you want to 
write portable code just because they are not standard. Unordered aims 
to be the Boost implementation of standard C++ hash containers.

For more information about the rationale and the evolution of unordered 
containers design see Matthew Austern's proposal:

A Proposal to Add Hash Tables to the Standard Library (revision 4)

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2003/n1456.html

Regards,

Ion