libstdc++/3552: missing hash function for std::string

[Phil Edwards]

The following reply was made to PR libstdc++/3552; it has been noted by GNATS.

From: Phil Edwards <phil@jaj.com>
To: Vadim Ogranovich <vograno@arbitrade.com>
Cc: "'goswin.brederlow@student.uni-tuebingen.de'" <goswin.brederlow@student.uni-tuebingen.de>,
   "'gcc-gnats@gcc.gnu.org'" <gcc-gnats@gcc.gnu.org>,
   "'Laurent.Bonnaud@inpg.fr'" <Laurent.Bonnaud@inpg.fr>,
   "'87063-quiet@bugs.debian.org'" <87063-quiet@bugs.debian.org>,
   "'gcc-bugs@gcc.gnu.org'" <gcc-bugs@gcc.gnu.org>
Subject: Re: libstdc++/3552: missing hash function for std::string
Date: Mon, 29 Apr 2002 15:09:32 -0400

 On Sat, Apr 27, 2002 at 02:37:52PM -0500, Vadim Ogranovich wrote:
 > Hi, I independently came across this bug. It seems like it was classified as
 > not a bug with no workaround posted. Is that the case? Thanks, Vadim
 
 Yes.  How can we possibly guess what a good hash function would be for
 arbitrary strings?  Efficiency of hashing is extremely dependant on the
 data being hashed.  You need to write one that's appropriate for your data;
 this will involve multiple experiments.
 
 There is std::collate::hash() for char*'s, but this is essentially a
 generic guess, and should only be used when you haven't yet had the time
 to come up with a more appropriate function.
 
 -- 
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