On Sun, Apr 8, 2012 at 5:46 AM, Vicente J. Botet Escriba <vicente.botet@wanadoo.fr> wrote:
Le 07/04/12 11:11, John M. Dlugosz a écrit :
On 4/6/2012 11:59 AM, Vicente J. Botet Escriba wrote:
As you are using std::move, &&, ... why not using directly the C++11 Thread library
provided with the compiler?

1) VS10 has && and std::move, but does not have the C++11 threading library.
 1b) A naive implementation (just starts a new OS thread) is not wanted.
 1c) but, an overly heavy implementation is not wanted either (i.e VS11 beta), because of additional dependencies in the program to distribute.
2) In the final code, the && will be optional, to avoid copies on compilers that support it, but must work with compilers that don't.
3) I need to preserve semantics of the code I'm replacing with modern C++ forms.
OK, I see.


BTW, Boost.Thread could not implement async using Boost, as Boost.Tuple, Boost.Bind
Boost.Fusion (Tuple) because these libraries dont manage with rvalue references.

I don't understand how that applies to my compiler problem.  It's telling me that

          task_object(F const& f_);   // << refers to look here
          task_object(F&& f_);         // <<<< Error here

are not a valid overloading set and instead conflict.

Sorry, I misunderstood your message.

After applying the following patch your example compiles. Please could you try it?

Could you also add a Trac ticket so that this is tracked?

HTH,
Vicente

Vicente,

It looks like you're just removing the task_object::task_object(F const &) overload. Seems strange that this overload existed but was/is never actually suppose to be used. ...except when F is a function pointer, I guess???

I sent a message to the list recently observing that one problem was the binding of F to be an lvalue reference (according to the error message, AFAICS), meaning that "F const &" and "F&&" are exactly the same type. Perhaps this behavior should be addressed directly?

- Jeff

Index: future.hpp
===================================================================
--- future.hpp    (revision 77816)
+++ future.hpp    (working copy)
@@ -1695,7 +1695,10 @@
            task_base<R>
        {
            F f;
-            task_object(F const& f_):
+//            task_object(F const& f_):
+//                f(f_)
+//            {}
+            task_object(R(*f_)()):
                f(f_)
            {}
 #ifndef BOOST_NO_RVALUE_REFERENCES
@@ -1703,6 +1706,7 @@
                f(f_)
            {}
 #else
+
 #if defined BOOST_THREAD_USES_MOVE
            task_object(boost::rv<F>& f_):
                f(boost::move(f_))
@@ -1736,7 +1740,10 @@
            task_base<void>
        {
            F f;
-            task_object(F const& f_):
+//            task_object(F const& f_):
+//                f(f_)
+//            {}
+            task_object(void(*f_)()):
                f(f_)
            {}
 #ifndef BOOST_NO_RVALUE_REFERENCES
@@ -1797,10 +1804,10 @@
        {}

        // construction and destruction
-        template <class F>
-        explicit packaged_task(F const& f):
-            task(new detail::task_object<R,F>(f)),future_obtained(false)
-        {}
+//        template <class F>
+//        explicit packaged_task(F const& f):
+//            task(new detail::task_object<R,F>(f)),future_obtained(false)
+//        {}
        explicit packaged_task(R(*f)()):
            task(new detail::task_object<R,R(*)()>(f)),future_obtained(false)
        {}

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