Re: [boost] [proto] _value doesn't enforce zero arity

9 Apr 2009

      troy d. straszheim wrote:
...
Now, per-class trace control (maybe via a trait?) this would be imho more useful.
Here's a possible interface for a boost::mpl-ized version of Steven 
Watanabe's template_profiler:

#define BOOST_MPL_ENABLE_TRACE
#include "trace.hpp"

//
// classes peppered with traces
//
template <typename T>
struct traceme
{
   BOOST_MPL_TRACE(traceme<T>);
};

template <typename T>
struct traceme_too
{
   BOOST_MPL_TRACE(traceme_too<T>);
};

template <typename T>
struct dont_trace_me
{
   BOOST_MPL_TRACE(dont_trace_me<T>);
};

//
//  trace-enabling traits
//
namespace boost {
   namespace mpl {
     namespace trace {

       template <typename T>
       struct enable<traceme<T> > : boost::mpl::true_ { };

       template <typename T>
       struct enable<traceme_too<T> > : boost::mpl::true_ { };

     }
   }
}
//
//  3. profit
//
int main(int, char**)
{
   traceme<int> ti;
   dont_trace_me<float> dtmf;
   traceme_too<void> tv;
}

The trace.hpp is attached, tested on gccs 4.3 and 4.2.

-t