I'm trying to follow the example given in http://www.boost.org/doc/libs/1_55_0/libs/utility/enable_if.html#sec:enable_if_0x

But VS2012 compiler gives: 

error C4519: default template arguments are only allowed on a class template

Is this supposed to work with VS2012?

Is there some other way to use enable_if in a conversion operator with VS2012?

Thnaks!