is_copy_assignable implementation added. It needs C++11 support to work reliable.

doc/is_copy_assignable.qbk

@@ -0,0 +1,51 @@
+[/ 
+  Copyright 2007 John Maddock.
+  Copyright 2014 Ion Gaztanaga.
+  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).
+]
+
+[section:is_copy_assignable is_copy_assignable]
+
+   template <class T>
+   struct is_copy_assignable : public __tof {};
+    
+__inherit If `T` is `CopyAssignable` (i.e. has an accessible explicit or implicit copy assignment operator),
+then inherits from __true_type, otherwise inherits from __false_type.  Type `T`
+must be a complete type.
+
+In other words, inherits from __true_type only if copy assignment of `T` from `const T &` is not 
+marked with `= delete`, `T` does not derives from `boost::noncopyable` and 
+is not marked with `BOOST_MOVABLE_BUT_NOT_COPYABLE(T)`.
+
+__compat If the compiler does not support partial-specialization of class 
+templates, then this template can not be used.
+
+If your compiler does not support C++11 deleted functions (`= delete`) or does not support  
+SFINAE for the deleted assignments, then derive your classes from `boost::noncopyable` or 
+mark them with `BOOST_MOVABLE_BUT_NOT_COPYABLE(T)` to show that class is non-assignable.
+
+Trait does not care about access modifiers, so if you see errors like this:
+
+      'T::operator=(const T&)' is private
+      boost/type_traits/is_copy_assignable.hpp:68:5: error: within this context
+
+then you are trying to call that macro for a structure with private assignment:
+
+      struct T {
+          // ...
+      private:
+          T &operator=(const T &);
+          // ...
+      };
+
+To fix that you must modify your structure, explicitly marking it as noncopyable (`= delete`, 
+`boost::noncopyable` or `BOOST_MOVABLE_BUT_NOT_COPYABLE(T)`) or explicitly 
+[link boost_typetraits.user_defined specializing the trait].
+
+
+__header ` #include <boost/type_traits/is_copy_assignable.hpp>` or ` #include <boost/type_traits.hpp>`
+
+[endsect]
+

doc/type_traits.qbk

@@ -69,6 +69,7 @@
 [def __is_empty [link boost_typetraits.reference.is_empty is_empty]]
 [def __is_const [link boost_typetraits.reference.is_const is_const]]
 [def __is_copy_constructible [link boost_typetraits.reference.is_copy_constructible is_copy_constructible]]
+[def __is_copy_assignable [link boost_typetraits.reference.is_copy_assignable is_copy_assignable]]
 [def __is_volatile [link boost_typetraits.reference.is_volatile is_volatile]]
 [def __is_abstract [link boost_typetraits.reference.is_abstract is_abstract]]
 [def __is_polymorphic [link boost_typetraits.reference.is_polymorphic is_polymorphic]]