Add result_type to lambda::ret. Fixes #1222

[SVN r53648]

include/boost/lambda/detail/lambda_functor_base.hpp

@@ -270,6 +270,8 @@ class lambda_functor_base<explicit_return_type_action<RET>, Args>
 public:
   Args args;
 
+  typedef RET result_type;
+
   explicit lambda_functor_base(const Args& a) : args(a) {}
 
   template <class SigArgs> struct sig { typedef RET type; };

test/Jamfile

@@ -30,4 +30,5 @@ test-suite lambda
     [ run operator_tests_simple.cpp ]
     [ run phoenix_control_structures.cpp ]
     [ run switch_construct.cpp ]
+    [ run ret_test.cpp ]
   ;      

test/ret_test.cpp

@@ -0,0 +1,53 @@
+//  ret_test.cpp  - The Boost Lambda Library -----------------------
+//
+// Copyright (C) 2009 Steven Watanabe
+//
+// Distributed under the Boost Software License, Version 1.0. (See
+// accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+//
+// For more information, see www.boost.org
+
+#include <boost/test/minimal.hpp>
+
+#include <boost/lambda/lambda.hpp>
+
+#include <boost/mpl/assert.hpp>
+#include <boost/type_traits/is_same.hpp>
+
+template<class R, class F>
+void test_ret(R r, F f) {
+    typename F::result_type x = f();
+    BOOST_MPL_ASSERT((boost::is_same<R, typename F::result_type>));
+    BOOST_CHECK(x == r);
+}
+
+template<class R, class F, class T1>
+void test_ret(R r, F f, T1& t1) {
+    typename F::result_type x = f(t1);
+    BOOST_MPL_ASSERT((boost::is_same<R, typename F::result_type>));
+    BOOST_CHECK(x == r);
+}
+
+class add_result {
+public:
+    add_result(int i = 0) : value(i) {}
+    friend bool operator==(const add_result& lhs, const add_result& rhs) {
+        return(lhs.value == rhs.value);
+    }
+private:
+    int value;
+};
+
+class addable {};
+add_result operator+(addable, addable) {
+    return add_result(7);
+}
+
+int test_main(int, char*[]) {
+    addable test;
+    test_ret(add_result(7), boost::lambda::ret<add_result>(boost::lambda::_1 + test), test);
+    test_ret(8.0, boost::lambda::ret<double>(boost::lambda::constant(7) + 1));
+
+    return 0;
+}