Hello Steven, thank you for helping me in debugging lambda.hpp! Steven Watanabe wrote:
AMDG
Torsten Maehne wrote:
* All checks involving the multiplication/division of boost::units::unit and boost::units::absolute<boost::units::unit> types are not compiling. The compiler complains about ambiguous overloads for operator* and operator/ (originating from Boost.Units and Boost.Lambda). Therefore they are currently commented out.
These shouldn't compile.
I modified the checks so that now units and absolute units are passed as well as arguments to the lambda expressions. Then the ambiguous overload errors disappear. However, for the absolute unit tests: <snip>
I left the non-compiling commented-out tests in place for documentation purposes.
I looked at the tests. I misunderstood what you were testing. Allowing multiplication _1 * meters e.g. would require disambiguating overloads.
I have tried to add specializations to lambda.hpp like the following: /// Partial specialization of return type trait for action /// boost::lambda::functor<T> * unit<Dim, System>. template<typename System, typename Dim, typename T> struct plain_return_type_2<arithmetic_action<multiply_action>, boost::lambda::lambda_functor<T>, boost::units::unit<Dim, System> > { typedef typename boost::units::multiply_typeof_helper< boost::lambda::lambda_functor<T>, boost::units::unit<Dim, System> >::type type; }; , to disambiguate the overloads. However the specialization seems to be not picked up by the compiler -- it still uses either: boost::lambda::functor<T> * Y or Y * unit<Dim, System> when uncommenting the check for bl::_1 * bu::meters in test_lambda.cpp. (Note: I didn't add the specialization to the attached corrected lambda.hpp.) Do you have an idea, what I'm doing wrong here?
* The check of unit<Dim1, System1> - unit<Dim2, System2> is not compiling. The compiler finds no matching definition of operator-.
Again these shouldn't compile.
This strikes me as being inconsistent, because it works for:
unit<Dim1, System1> + unit<Dim2, System2>
I see. I didn't understand what you were testing, again. The problem is in units/lambda.hpp line 390 ff.
/// Partial specialization of return type trait for action /// unit<Dim1, System1> - unit<Dim2, System2>. template<typename Dim1, typename Dim2, typename System1, typename System2> struct plain_return_type_2<arithmetic_action<minus_action>, boost::units::unit<Dim1, System1>, boost::units::unit<Dim2, System2> > { BOOST_STATIC_ASSERT((boost::is_same<System1, System2>::value == true)); typedef typename boost::units::subtract_typeof_helper< boost::units::*quantity*<Dim1, System1>, boost::units::*quantity*<Dim2, System2> >::type type; };
These two quantities ought to be units.
Thanks for pointing me to this nasty copy & paste error. I corrected it in the attached new lambda.hpp. Best regards, Torsten