Shouldn't the default arity be set to be big enough for all Boost libraries instead? Wouldn't several non-overriding defaults be a pain for users? Should the biggest of the defaults from any Boost library should be included first by the users?
Not sure... I don't think there are that many Boost libraries that use Boost.Parameter so I don't believe that you'd have that too many conflicting defaults.
Or is it OK with successive redefinition (if made larger?) of the arity? (Hopefully someone can make sense of this..)
Successive redefinition between compiled files but it probably won't work within the same translation unit. You'd have to undef all the header guards, and that's probably going to result in some serious violations of the ODR (one definition rule). I'm probably going to end up overriding the default in my include chain, but I think the best solution may simply be to change the default in Boost.Parameter. Andrew Sutton asutton@cs.kent.edu