From 4d635501ab9eb2fc78119ea5c47dfe6b03f7d970 Mon Sep 17 00:00:00 2001
From: Douglas Gregor <doug.gregor@gmail.com>
Date: Tue, 14 May 2002 14:18:36 +0000
Subject: [PATCH] function_base.hpp: function_template.hpp:   - Revert to older
 implementation of has_empty_function (Metrowerks doesn't     handle
 is_base_and_derived correctly)

[SVN r13854]
---
 include/boost/function/function_base.hpp     | 16 +++++-----------
 include/boost/function/function_template.hpp | 12 ++----------
 2 files changed, 7 insertions(+), 21 deletions(-)

diff --git a/include/boost/function/function_base.hpp b/include/boost/function/function_base.hpp
index f817e6a..d827538 100644
--- a/include/boost/function/function_base.hpp
+++ b/include/boost/function/function_base.hpp
@@ -341,20 +341,14 @@ namespace boost {
 
   namespace detail {
     namespace function {
-      // The result is not a Boost.Function object, so we assume that this
-      // target is not empty
-      template<typename FunctionObj>
-      inline bool has_empty_target(const FunctionObj&, truth<false>)
+      inline bool has_empty_target(const function_base* f)
       {
-	return false;
+        return f->empty();
       }
 
-      // The result is a Boost.Function object, so query whether it is empty
-      // or not
-      template<typename FunctionObj>
-      inline bool has_empty_target(const FunctionObj& f, truth<true>)
-      { 
-        return f.empty();
+      inline bool has_empty_target(...)
+      {
+        return false;
       }
     } // end namespace function
   } // end namespace detail
diff --git a/include/boost/function/function_template.hpp b/include/boost/function/function_template.hpp
index ab0d18e..d7057c7 100644
--- a/include/boost/function/function_template.hpp
+++ b/include/boost/function/function_template.hpp
@@ -425,11 +425,7 @@ namespace boost {
     template<typename FunctionObj>
     void assign_to(FunctionObj f, detail::function::function_obj_tag)
     {
-      typedef detail::function::truth<
-                boost::is_base_and_derived<function_base, FunctionObj>::value>
-	is_boost_function;
-
-      if (!detail::function::has_empty_target(f, is_boost_function())) {
+      if (!detail::function::has_empty_target(addressof(f))) {
         typedef 
           typename detail::function::BOOST_FUNCTION_GET_FUNCTION_OBJ_INVOKER<
                                        FunctionObj,
@@ -463,11 +459,7 @@ namespace boost {
     void assign_to(const reference_wrapper<FunctionObj>& f, 
                    detail::function::function_obj_ref_tag)
     {
-      typedef detail::function::truth<
-                boost::is_base_and_derived<function_base, FunctionObj>::value>
-	is_boost_function;
-
-      if (!detail::function::has_empty_target(f.get(), is_boost_function())) {
+      if (!detail::function::has_empty_target(f.get_pointer())) {
         typedef 
           typename detail::function::BOOST_FUNCTION_GET_FUNCTION_OBJ_INVOKER<
                                        FunctionObj,