On Tue, Apr 12, 2011 at 9:00 AM, Stewart, Robert <Robert.Stewart@sig.com>wrote:
I don't care for boost::enabler because "boost::" and "enable" are repeated (the first "enable" is in "enable_when") and a long line is made even longer. Note that the use of boost::enabler is optional: the type is void *&, so, for example, "= 0" works just as well and might be thought to negate enable_when.
You can't initialize a reference template parameter to 0 (I don't believe you can for pointer parameters either for that matter). If we go the route of making _when templates (which I'm not sure is a great idea as it doubles the number of templates in Boost.Enable_If), the syntax that I think would be best would be: typename enable_when< is_arithmetic< T > >::type = {} where ::type would refer to a detail enum, but unfortunately {} doesn't seem to be a valid default for a template parameter. Does anyone know the rationale for this offhand? I don't immediately see a problem with it. I haven't looked at the standard but Comeau doesn't allow such defaults either so I assume it's not just a broken implementation. -- -Matt Calabrese