Terje Slettebø <tslettebo@broadpark.no> writes:
There are also similar facilites as BOOST_IS_XXXABLE_PREFIX()/BOOST_IS_XXXABLE_POSTFIX() in the operator/concept traits library, although they are not documented, as such detection for all the overloadable operators is already defined in the library, so the user shouldn't really have a need for it. Nevertheless, they are found in the operator_traits/detail/unop.hpp (prefix), unop2.hpp (postfix) and binop.hpp headers.
The current version of is_xxxable.hpp in Yahoo Files does seem to have some problems, when it comes to implicit conversions.
I discovered another problem with these macros after I uploaded them. The original 'is_dereferenceable' implementation relied upon special handling for fundamental types. The reason is that attempting to dereference something like an 'int' or 'float' is going to cause a compiler error no matter what, even if there is a last resort 'operator*'. To solve this problem, I rigged 'is_dereferenceable' to return false for all fundamental types. (Pointers are not considered fundamental types.) This special handling was carried over into the 'is_xxxable' macros, and it doesn't generalize to other operators. For instance, if I use 'BOOST_IS_XXXABLE_PREFIX' to generate 'is_incrementable', I get a metafunction that returns 'false' for integers. Of course, this problem can be fixed, but probably not without some special handling for specific fundamental types and/or operators, which kind of defeats the purpose of having a generalized macro. -- Alex Chovanec NIF and Engineering Division Computing Applications and Research Department Lawrence Livermore National Laboratory