Hi Aristid,
Worse, I think you can't fix the set of currencies at compile-time. Even if you were willing to change your program whenever a new currency is added to the set of world currencies (admittedly relatively rarely but it does happen), you might quickly want to add stuff like wheat or stocks (if only for completeness sake).
Any ideas how to deal with this properly?
I really don't know of a way (at least in C++) to provide zero overhead compile-time dimensional analysis where you don't specify the set of currencies in advance. mcs::units allows arbitrary (or nearly so) unit conversions at runtime, but is restricted to a static set of fundamental units (whatever they may be). The kind of application you're envisioning probably calls for a runtime system or (even better) a specific library for dealing with currency... Matthias