[boost] Re: Simplifying promote_traits

From: J.F.K. (beholder_at_[hidden])
Date: 2003-10-10 00:16:01

hello, Neal
I've used this promote_traits<> class in my project
try it if you wish
and I'll be very interested in any ideas to make it more 
general, but not as general as Joel solution :)

regards, Oleg

----- Original Message ----- 
From: "Neal D. Becker" <nbecker_at_[hidden]>
Newsgroups: gmane.comp.lib.boost.devel
Sent: Tuesday, 07 October, 2003 18:55
Subject: Simplifying promote_traits

> I frequently need to write arithmetic algorithms which may need to infer the 
> type of intermediate variables.  These algorithms will be used with mixed 
> types, such as:
> 
> double, std::complex<double>
> int, std::complex<int>
> 
> I have looked at boost/numeric/ublas/traits.hpp, at promote_traits class.  It 
> seems that this suffers from a quadratic explosion, needing to define a 
> specialization for every combination of <T1, T2>.  
> 
> I think it would be simpler to use boost::is_convertible.  The type of the 
> product of two types T1, T2 is T1 if T2 is convertible to T1, T2 if T1 is 
> convertible to T2, and undefined otherwise.
> 
> This might be overly general, but I think the simplicity of the design is more 
> significant.
> 
> Any thoughts?
> 
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