Re: [Boost-users] [math][tools][units] generic libraries not genericenough

Subject: Re: [Boost-users] [math][tools][units] generic libraries not genericenough
From: alfC (alfredo.correa_at_[hidden])
Date: 2011-08-26 05:55:13

Hi again, 

 Just to be fair, I have to add that boost.units needs a small set of 
additions in order to make easier and encourage other libraries to be 
generic. At least two:

 1) division and multiplication by integer
currently this fails to compile

 mid = (min + max)/2; // fails

because 2 is an integer.

 2) comparison with "symbolic" 0, i.e. null,
for consistency with zero constructor. Currently

 boost::quantity<si::length> a(0); // ok currently
 if(a==0) ...; //not ok currently, workaround if(a == quantity<...>(0))
 if(a > 0) ...; //not ok currently, workaround if(a > quantity<...>(0))
 a = 0; //not ok currently

these two operation are very common in math applications (like root finding 
:) ).

I have an implementation of 1) and 2) of my own (except operator= which is 
not possible to have a non member function),
I think if these very basic things are incorporated in boost.units then 
libraries with boost.units in mind will be easier to develop.

Alfredo