As I wrote before, you can specialize numeric_limits class with your custom type: template<class T> struct my_numeric_limits_impl { static T min() { return boost::decimal::decimal_limits<T>::min(); } }; namespace std { template<> class numeric_limits<your_custom_type1> : public my_numeric_limits_impl<your_custom_type1> {}; template<> class numeric_limits<your_custom_type2> : public my_numeric_limits_impl<your_custom_type2> {}; } What is wrong on this approach? The only problem I see here is the the customer must include the specialization of numeric limits. But this can be easily solved if you put in the same header where your_custom_type is defined. So everyone using yyour_custom_type will automatically include numeric_limits and if needed use the correct version. -----Original Message----- From: james.jones@firstinvestors.com [mailto:james.jones@firstinvestors.com] Sent: Mittwoch, 7. März 2007 22:12 To: boost-users@lists.boost.org Subject: Re: [Boost-users] [enable_if] using enable_if to extendstd::numeric_limits? From: me22 <me22.ca@gmail.com>

I don't think you can "extend" classes that already exist. Note, for example, that boost has integer_traits, and doesn't try to modify numeric_limits.

Why do you want the concept to be in numeric_limits? Can you not simply use is_decimal_type?

I should be more precise - by "extend" I really mean "specialize". I'd like to provide specializations for numeric_limits for my new decimal types. I can certainly just provide my own decimal_limits class (and have implemented this already), but the idea is to create a drop-in replacement for, say, double - and existing code likely uses numeric_limits<T> with T=double already, so being able to provide this with T=my_decimal_type would be ideal. - James Jones Administrative Data Mgmt. Webmaster 375 Raritan Center Pkwy, Suite A Data Architect Edison, NJ 08837 _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users