Daniel Frey <daniel.frey@aixigo.de> writes:
Thorsten Ottosen wrote:
"Daniel Frey" <daniel.frey@aixigo.de> wrote in message news:cfhteq$piv$1@sea.gmane.org... |Hm, good point. The only "solution" I could come up with is shown below, |but I don't know how portable/robust it is. | | template< typename T > | internal f( const T& x ) | { | if( sizeof( f(x),internal() ) == sizeof( char ) ) { | // Non-ADL-implementation | std::cout << 1 << std::endl; | } | else { | // ADL-forwarder | f( x ); | } | return internal(); | } why do you return an internal here? I mean, weed want to return f(x).
But we need to detect which f(x) is choosen in the sizeof. The ADL f(x) won't return internal, thus the operator, isn't applied, thus the sizeof( f(x),internal() ) is not sizeof( char ). How else could you detect which f(x) would be choosen? The above example also "wants" to return void, thus it should work. For non-void return types, the class internal' must be more complicated.
But maybe someone else has a better (and robust enough) idea how to detect which f(x) would be called...
You can use something like what boost/detail/is_incrementable.hpp is doing, but I think that's basically the same technique you're using. And this seems to be exactly what I was talking about on the NG when I suggested removing ambiguity by detecting whether there's a function that could be found via ADL... or am I missing something? -- Dave Abrahams Boost Consulting http://www.boost-consulting.com