subtraction of dimensionless quantities produce surprising result about units

[correaa]

Digging a little further I realize that the problem is mainly with pre-subtraction and pre-addition int - dimlessQ and int + dimlessQ. At the moment, multiplication, division and post-addition and post-substraction gives correct result. However there still a glitch that is that dimlessQ + int and dimlessQ - int return a double (or the underlying type of dimlessQ) instead of dimlessQ, which I expect is the expected result.

So , in summary I think this is resolved by adding these operation to the boost units namespace:
(Perhaps the only extra case is for unsigned int, long, unsigned long, etc)

namespace boost{
namespace units{
#if 1
template<class S, class Y>
inline
quantity<BOOST_UNITS_DIMENSIONLESS_UNIT(S), Y>
operator-(int i,
    const quantity<BOOST_UNITS_DIMENSIONLESS_UNIT(S), Y>& q2)
{
    typedef quantity<BOOST_UNITS_DIMENSIONLESS_UNIT(S),Y> quantity_type;
    return quantity_type::from_value(i - q2.value());
}
template<class S, class Y>
inline
quantity<BOOST_UNITS_DIMENSIONLESS_UNIT(S), Y>
operator-(
    const quantity<BOOST_UNITS_DIMENSIONLESS_UNIT(S), Y>& q1, int i)
{
    typedef quantity<BOOST_UNITS_DIMENSIONLESS_UNIT(S),Y> quantity_type;
    return quantity_type::from_value(q1.value() - i);
}
template<class S, class Y>
inline
quantity<BOOST_UNITS_DIMENSIONLESS_UNIT(S), Y>
operator+(int i,
    const quantity<BOOST_UNITS_DIMENSIONLESS_UNIT(S), Y>& q2)
{
    typedef quantity<BOOST_UNITS_DIMENSIONLESS_UNIT(S),Y> quantity_type;
    return quantity_type::from_value(i + q2.value());
}
template<class S, class Y>
inline
quantity<BOOST_UNITS_DIMENSIONLESS_UNIT(S), Y>
operator+(
    const quantity<BOOST_UNITS_DIMENSIONLESS_UNIT(S), Y>& q1, int i)
{
    typedef quantity<BOOST_UNITS_DIMENSIONLESS_UNIT(S),Y> quantity_type;
    return quantity_type::from_value(q1.value() + i);
}
#endif
}}

[swatanabe]

AMDG

On 10/05/2018 01:07 AM, Alfredo Correa wrote: In a generic environment one needs to write generic function involving integer integrals. ``` template<class A, class B> auto f(A a, B b){return 1 - a/b;} ``` Feeding `f(1.,2.)` gives `0.5`. However if one feeds `f(1.*si::meter, 2.*si::meter)` insted one gets `1` and of type `int`.

I can't reproduce this with VS2017. What compiler are you using? In Christ, Steven Watanabe