On 3/15/2011 3:00 AM, Vicente Botet wrote:
Frédéric Bron wrote:
For example: has_operator_unary_minus< class RHS, class RET=RHS> has_operator_minus_assign< class LHS, class RHS=LHS, class RET=LHS> This would take care of most of the normal use cases.
I think it is best to have the default behavior to forget about the return type. Why would you impose return type to be LHS? It is fine for +, -, ... when RHS=LHS but when you start to deal with different types, I think it just adds confusion. has_operator_plus<double, int> would then check for a return type "double" while has_operator_plus<int, double> for a return type int. You would break the symmetry of these operators.
User wanting symmetry could use common_type<LHS,RHS> in this case. But using it as default is not good idea as common_type is not always defined. So I agree to change the default behavior to don't check.
When is common_type not defined? I see no documentation in Boost.TypeTraits.CommonType mentioning it not being available for certain compilers... - Jeff