function_base.hpp:

- Remove safe_bool conversion and operator! from class function_base

function_template.hpp:
  - Add safe_bool conversion and operator!
  - operator! returns bool, not safe_bool (Peter Dimov)

reference.html:
  - Document above change


[SVN r15356]

doc/reference.html

@@ -17,8 +17,6 @@
   {
     <b>typedef</b> <em>implementation-defined</em> safe_bool;
     <a href="#empty"><b>bool</b> empty() <b>const</b></a>;
-    <a href="#bool"><b>operator</b> safe_bool() <b>const</b></a>;
-    <a href="#not">safe_bool <b>operator!</b>() <b>const</b></a>;
   };
 
   // For <i>N</i> in [0, <i>MAX_ARGS</i>]
@@ -66,6 +64,10 @@
     <a href="#functionN_swap"><b>void</b> swap(function<i>N</i><b>&amp;</b>)</a>;
     <a href="#functionN_clear"><b>void</b> clear()</a>;
 
+    <i>// Boolean context</i>
+    <a href="#bool"><b>operator</b> safe_bool() <b>const</b></a>;
+    <a href="#not"><b>bool</b> <b>operator!</b>() <b>const</b></a>;
+
     <i>// Invocation</i>
     <a href="#functionN_call_const">result_type <b>operator</b>()(Arg1 a1, Arg2 a2, <i>...</i>, Arg<i>N</i> a<i>N</i>) <b>const</b></a>;
   };
@@ -146,20 +148,6 @@
   <li><b>Throws</b>: will not throw.</li>
 </ul>
 
-<p> <a name="bool"><code><b>operator</b> safe_bool() <b>const</b></code></a>
-<ul>
-  <li><b>Returns</b>: <code>safe_bool</code> equivalent of <code>!<a href="#empty">empty</a>()</code></li>
-  <li><b>Throws</b>: will not throw.</li>
-  <li><b>Notes</b>: The <code>safe_bool</code> type can be used in contexts where a <b>bool</b> is expected (e.g., an <b>if</b> condition); however, implicit conversions (e.g., to <b>int</b>) that can occur with <b>bool</b> are not allowed, eliminating some sources of user error.
-</ul>
-
-<p> <a name="not"><code>safe_bool <b>operator!</b>() <b>const</b></code></a>
-<ul>
-  <li><b>Returns</b>: <code>safe_bool</code> equivalent of <code><a href="#empty">empty</a>()</code></li>
-  <li><b>Throws</b>: will not throw.</li>
-  <li><b>Notes</b>: See <a href="#bool"><code>safe_bool</code> conversion</a>
-</ul>
-
 <h2><a name="functionN">Class template <code>function<i>N</i></code></a></h2>
 <p> Class template <code>function<i>N</i></code> is actually a family of related classes <code>function0</code>, <code>function1</code>, etc., up to some implementation-defined maximum. In this context, <code><i>N</i></code> refers to the number of parameters and <code>f</code> refers to the implicit object parameter.
 
@@ -239,6 +227,19 @@
   <li><b>Postconditions</b>: <code><a href="#empty">empty</a>()</code>.</li>
 </ul>
 
+<p> <a name="bool"><code><b>operator</b> safe_bool() <b>const</b></code></a>
+<ul>
+  <li><b>Returns</b>: <code>safe_bool</code> equivalent of <code>!<a href="#empty">empty</a>()</code></li>
+  <li><b>Throws</b>: will not throw.</li>
+  <li><b>Notes</b>: The <code>safe_bool</code> type can be used in contexts where a <b>bool</b> is expected (e.g., an <b>if</b> condition); however, implicit conversions (e.g., to <b>int</b>) that can occur with <b>bool</b> are not allowed, eliminating some sources of user error.
+</ul>
+
+<p> <a name="not"><code><b>bool</b> <b>operator!</b>() <b>const</b></code></a>
+<ul>
+  <li><b>Returns</b>: <code>this-&gt;empty()</code></li>
+  <li><b>Throws</b>: will not throw.</li>
+</ul>
+
 <p> <a name="functionN_call_const"><code> result_type <b>operator</b>()(Arg1 a1, Arg2 a2, <i>...</i>, Arg<i>N</i> a<i>N</i>) <b>const</b>;</code></a>
 <ul>
   <li><b>Requires</b>: <code>!<a href="#empty">empty</a>()</code>.</li>

include/boost/function/function_base.hpp

@@ -278,25 +278,6 @@ namespace boost {
                            detail::function::any_pointer, 
                            detail::function::functor_manager_operation_type);
     detail::function::any_pointer functor;
-
-#if (defined __SUNPRO_CC) && (__SUNPRO_CC <= 0x530) && !(defined BOOST_NO_COMPILER_CONFIG)
-    // Sun C++ 5.3 can't handle the safe_bool idiom, so don't use it
-    operator bool () const { return !this->empty(); }
-#else
-  private:
-    struct dummy {
-      void nonnull() {};
-    };
-
-    typedef void (dummy::*safe_bool)();
-
-  public:
-    operator safe_bool () const 
-      { return (this->empty())? 0 : &dummy::nonnull; }
-
-    safe_bool operator!() const
-      { return (this->empty())? &dummy::nonnull : 0; }
-#endif
   };
 
   /* Poison comparison between Boost.Function objects (because it is 

include/boost/function/function_template.hpp

@@ -419,6 +419,25 @@ namespace boost {
       invoker = 0;
     }
 
+#if (defined __SUNPRO_CC) && (__SUNPRO_CC <= 0x530) && !(defined BOOST_NO_COMPILER_CONFIG)
+    // Sun C++ 5.3 can't handle the safe_bool idiom, so don't use it
+    operator bool () const { return !this->empty(); }
+#else
+  private:
+    struct dummy {
+      void nonnull() {};
+    };
+
+    typedef void (dummy::*safe_bool)();
+
+  public:
+    operator safe_bool () const 
+      { return (this->empty())? 0 : &dummy::nonnull; }
+
+    bool operator!() const
+      { return this->empty(); }
+#endif
+
   private:
     void assign_to_own(const BOOST_FUNCTION_FUNCTION& f)
     {