[boost] Re: [review] hash functions

From: Pavel Vozenilek (pavel_vozenilek_at_[hidden])
Date: 2005-03-09 14:01:16

 ______________________________________________
>> 9. Win32 Intel fix: by default I get error:
>>
>> C:\work\reviews\hash\hash\boost/functional/hash.hpp(226): error:
>> no instance of overloaded function "boost::hash_value" matches the 
>> argument list
>>             argument types are: (const test::custom)
>>               return hash_value(val);
>>
>>
>>
>> one needs to add compiler option:
>>     /Qoption,c,--arg_dep_lookup
>>
>> to enable ADL with Intel when emulating VC6.
>
> The custom test is only going to work on compilers with ADL - that's 
> deliberate so that the test results will show what works and what doesn't.
>
> On compilers without ADL, you'll have to add the overload to the boost 
> namespace.
>
Could there be page describing what works where and
what workarounds may be needed?

______________________________________________
>> 10. performance: wouldn't it be better to provide
>>     hand written specialization for std::string/wstring
>>     instead of relying on hash_range/combine?
>>
>>
>>     The compiler may not optimize chain of functions
>>     out/pass parameters in most efficient way/
>>     keep most data in registers.
>>
>>
>>     It's just feeling, I didn't do any measurements.
>
> Maybe. I would want to do some profiling before doing that sort of 
> optimisation.
>
If possible within larger app. Compiler may get under time pressure
there.

/Pavel