Stjepan Rajko a &eacute;crit :<br />&gt; What is your use case? I found
this sort of thing useful for finding<br />&gt; out whether result_of
would work for a specific set of arguments. Is your<br />&gt; metafunction
intended for testing whether result_of would work for _some_<br />&gt;
(whichever) set of arguments? (it doesn't quite do that<br />&gt; because
it doesn't check that result has a nested type typedef).<br /><br />I was
trying to use it as a simple traits to see if a given type fullfilled the
result_of protocol <br />whatever the arguments used. It works ok for the
result_type variant but now I see it's still incomplete. The problem is
that I can't see, for an arbitrary result structure, how I can see if it
actually has at least one overload that has a proper nested type
typedef.<br /><br />Typical use is :<br /><br />For F a given type,&nbsp;
support_result_of_protocol&lt;F&gt;::type evaluates as a compile time
boolean indicating if either F has a nested result structure or
result_type typedef. It doesn't make any assumptions on wether or nor
result is correcly implemented.<br /><br />As for testing if a particuliar
set of arguments produces a valid result_of, one can easily do :<br /><br
/>template&lt; class F<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ,
template&lt;class&gt; class T = boost::result_of&lt;F&gt;::type<br
/>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &gt; struct valid_impl<br
/>{<br />&nbsp; typedef void type;<br />};<br /><br />template&lt;class F,
class EnableIf = void&gt;<br />struct produce_valid_result_of :
boost::false_type {};<br /><br />template&lt;class F&gt;<br />struct
produce_valid_result_of&lt;F,typename valid_impl&lt;F&gt;::type&gt; :
boost::true_type {};<br /><br />or did I miss something in your question
?<br />