From 89bba6d009cb553f4b4e152a82febedbca80a352 Mon Sep 17 00:00:00 2001
From: Robert Ramey <ramey@rrsd.com>
Date: Thu, 22 Nov 2007 08:17:38 +0000
Subject: [PATCH] tested with statically loaded dlls

[SVN r41298]
---
 doc/contents.html           |  14 +-
 doc/extended_type_info.html |  94 +++++++-------
 doc/serialization.html      |   6 +-
 doc/special.html            | 250 +++++++++++++++++++++---------------
 doc/void_cast.html          |   4 +-
 5 files changed, 213 insertions(+), 155 deletions(-)

diff --git a/doc/contents.html b/doc/contents.html
index 62107cf9..9a01c8ff 100644
--- a/doc/contents.html
+++ b/doc/contents.html
@@ -148,6 +148,7 @@ function initialize() {
           <dt><img style="display:none" src="plus.gif" id="derivedpointers"><a target="detail" href="serialization.html#derivedpointers">Pointers to Objects of Derived Classes</a>
           <dd><div id="derivedpointers_detail"><dl class="page-index">
             <dt><img style="display:none" src="dot.gif"><a target="detail" href="serialization.html#registration">Registration</a>
+            <dt><img style="display:none" src="dot.gif"><a target="detail" href="serialization.html#export">Export</a>
             <dt><img style="display:none" src="dot.gif"><a target="detail" href="serialization.html#instantiation">Instantiation</a>
             <dt><img style="display:none" src="dot.gif"><a target="detail" href="serialization.html#selectivetracking">Selective Tracking</a>
             <dt><img style="display:none" src="dot.gif"><a target="detail" href="serialization.html#runtimecasting">Runtime Casting</a>
@@ -262,8 +263,8 @@ function initialize() {
       <dt><img style="display:none" src="dot.gif"><a target="detail" href="pimpl.html">PIMPL</a>
       <dt><img style="display:none" src="dot.gif"><a target="detail" href="derivation.html">Derivation from an Existing Archive Class</a>
     </dl></div></dd>
-    <dt><img style="display:none" src="plus.gif" id="miscellaneous">Miscellaneous
-    <dd><div id="miscellaneous_detail"><dl class="page-index">
+    <dt><img style="display:none" src="plus.gif" id="otherclasses">Other Classes
+    <dd><div id="otherclasses_detail"><dl class="page-index">
       <dt><img style="display:none" src="plus.gif" id="extended_type_info"><a target="detail" href="extended_type_info.html"><code>extended_type_info</code></a>
       <dd><div id="extended_type_info_detail"><dl class="page-index">
         <dt><img style="display:none" src="dot.gif"><a target="detail" href="extended_type_info.html#motivation">Motivation</a>
@@ -278,6 +279,15 @@ function initialize() {
       <dt><img style="display:none" src="dot.gif"><a target="detail" href="dataflow.html">Dataflow Iterators</a>
       <dt><img style="display:none" src="dot.gif"><a target="detail" href="smart_cast.html"><code>smart_cast</code></a>
       <dt><img style="display:none" src="dot.gif"><a target="detail" href="static_warning.html"><code>BOOST_STATIC_WARNING</code></a>
+      <dt><img style="display:none" src="plus.gif" id="singleton"><a target="detail" href="singleton.html"><code>singleton</code></a>
+      <dd><div id="singleton_detail"><dl class="page-index">
+        <dt><img style="display:none" src="dot.gif"><a target="detail" href="singleton.html#motivation">Motivation</a>
+        <dt><img style="display:none" src="dot.gif"><a target="detail" href="singleton.html#features">Features</a>
+        <dt><img style="display:none" src="dot.gif"><a target="detail" href="singleton.html#classinterface">Class Interface</a>
+        <dt><img style="display:none" src="dot.gif"><a target="detail" href="singleton.html#requirements">Requirements</a>
+        <dt><img style="display:none" src="dot.gif"><a target="detail" href="singleton.html#examples">Examples</a>
+        <dt><img style="display:none" src="dot.gif"><a target="detail" href="singleton.html#multithreading">Multi-Threading</a>
+      </dl></div></dd>
     </dl></div></dd>
     <!--
     <dt><img style="display:none" src="dot.gif"><a target="detail" href="configuration.html">Configuration Information</a></dt>
diff --git a/doc/extended_type_info.html b/doc/extended_type_info.html
index a785e140..822c043a 100644
--- a/doc/extended_type_info.html
+++ b/doc/extended_type_info.html
@@ -61,11 +61,6 @@ the following functions
     different applications. In fact, including different headers in different
     name spaces is an accepted method used to avoid name space conflicts.
     Thus the namespace::class_name can't be used as a key.
-  <li>
-    We may want the ability to serialize objects through a base class even though
-    they have no <code style="white-space: normal">virtual</code> function.  That
-    is, objects of classes which are not polymorphic in the strict C++ sense.  This
-    is not supported by the standard system.
   <li>
     There exists the possibility that different classes use different type id 
     mechanism.  The class header might include this information. If we want to 
@@ -80,8 +75,8 @@ following features:
 <ul>
   <li>
     Builds a set of <a target="extended_type_info.hpp" href = "../../../boost/serialization/extended_type_info.hpp">
-    <code style="white-space: normal">extended_type_info</a></code> records - one for each type known
-    to the program.
+    <code style="white-space: normal">extended_type_info</a></code> records - one for each type
+    serialized.
   <li>
     permits association of an arbitrary string key with a type.  Often this key would
     be the class name - but it doesn't have to be.  This key is referred to as
@@ -104,40 +99,52 @@ in order to construct types serialized through a base class pointer.
 namespace boost { 
 namespace serialization {
 
-class BOOST_SERIALIZATION_DECL extended_type_info : 
-    private boost::noncopyable 
+class extended_type_info
 {
 protected:
     // this class can't be used as is. It's just the 
     // common functionality for all type_info replacement
     // systems.  Hence, make these protected
-    extended_type_info();
-    ~extended_type_info();
     const char * m_key;
-    extended_type_info(const char * type_info_key);
+    extended_type_info(const unsigned int type_info_key);
+    ~extended_type_info();
 public:
     void key_register(const char *key);
-    const char * get_key() const;
+    const char * get_key() const {
+        return m_key;
+    }
+    bool operator<(const extended_type_info &rhs) const;
+    bool operator==(const extended_type_info &rhs) const;
+    bool operator!=(const extended_type_info &rhs) const {
+        return !(operator==(rhs));
+    }
     static const extended_type_info * find(const char *key);
 };
 
-bool operator<(const extended_type_info &rhs) const;
-bool operator==(const extended_type_info &rhs) const;
-
 } // namespace serialization 
 } // namespace boost
 </code></pre>
-
-There must be one and only one <code style="white-space: normal"><a target="extended_type_info.hpp" href = "../../../boost/serialization/extended_type_info.hpp">extended_type_info</a></code>
-instance created for each type. For this reason, this class is marked is derived from
-<code style="white-space: normal">boost::noncopyable</code>. 
-
+<p>
+Generally, there will be one and only one
+<code style="white-space: normal"><a target="extended_type_info.hpp" href = "../../../boost/serialization/extended_type_info.hpp">extended_type_info</a></code>
+instance created for each type.  However, this is enforced only at the executable
+module level.  That is, if a program includes some shared libraries or DLLS,
+there may be more than one instance of this class correponding to a particular type.
+For this reason the comparison functions below can't just compare the addresses of 
+this instance but rather must be programmed to compare the the actual information 
+the instances contain.
 <dl>
 
 <dt><h4><pre><code>
-extended_type_info(const char * type_info_key);</code></pre></h4></dt>
+extended_type_info(unsigned int type_info_key);
+</code></pre></h4></dt>
 <dd>
 This constructor should be called by all derived classes.
+The argument should be the particular implementation. For
+this default implementation base on typeid(), this is the 
+value 1.  Each system must have its own integer.  This value
+is used to permit the inter-operability of different typeinfo
+systems.
 </dd>
 
 <dt><h4><pre><code>
@@ -153,6 +160,8 @@ For this purpose, it must be the same in all program instances which
 refer to the same type.
 <p>
 It may sometimes be referred to as a GUID - a <b>G</b>lobal <b>U</b>nique <b>ID</b>entifier.
+</dd>
+
 <dt><h4><pre><code>
 const char *get_key() const;
 </code></pre></h4></dt>
@@ -162,35 +171,25 @@ instance.  If no key has been associated with the instance, then a NULL is retur
 </dd>
 
 <dt><h4><pre><code>
-// in order
-bool operator==(
-    const extended_type_info & lhs, 
-    const extended_type_info & rhs
-);
-bool operator<(
-    const extended_type_info & lhs, 
-    const extended_type_info & rhs
-);
-
-} // namespace serialization 
-} // namespace boost
+bool operator<(const extended_type_info & rhs) const;
+bool operator==(const extended_type_info & rhs) const;
+bool operator!=(const extended_type_info & rhs) const;
 </code></pre></h4></dt>
 <dd>
-These non-member functions are used to compare two 
+These functions are used to compare two 
 <a target="extended_type_info.hpp" href = "../../../boost/serialization/extended_type_info.hpp">
 <code style="white-space: normal">
 extended_type_info
 </code> 
 </a>
-objects. They a strict total ordering on all instances of this class and
-are used to implement the following.
+objects. They a strict total ordering on all instances of this class.
 
 <dt><h4><pre><code>
 static const extended_type_info * find(const char *key);
 </code></pre></h4></dt>
 <dd>
-Given a character string key or <strong>GUID</strong>, return the address of the 
-unique corresponding <code style="white-space: normal"><a target="extended_type_info.hpp" href = "../../../boost/serialization/extended_type_info.hpp">extended_type_info</a></code>
+Given a character string key or <strong>GUID</strong>, return the address of a 
+corresponding <code style="white-space: normal"><a target="extended_type_info.hpp" href = "../../../boost/serialization/extended_type_info.hpp">extended_type_info</a></code>
 object. 
 
 </dl>
@@ -224,8 +223,8 @@ this just amounts to returning the address of this static object.
 
 <dt><h4><code style="white-space: normal"><pre>
 template&lt;class ETI&gt;
-static const extended_type_info *
-ETI::get_derived_extended_type_info(const T & t);
+const extended_type_info *
+ETI::get_derived_extended_type_info(const T & t) const;
 </pre></code></h4></dt>
 <dd>
 Return a pointer to the 
@@ -235,7 +234,14 @@ the "true type" of the type T.  The "true type" is the lowest type in the
 hierarchy of classes.  The type T can always be cast to the "true type" with
 a static cast.  Implemention of this function will vary among type id systems
 and sometimes will make presumptions about the type T than can be identified
-with a particular <code style="white-space: normal">extended_type_info implementation</code>.
+with a particular <code style="white-space: normal">extended_type_info</code> implementation.
+</dd>
+
+<dt><h4><code style="white-space: normal"><pre>
+bool ETI::less_than(const extended_type_info &rhs) const;
+</pre></code></h4></dt>
+<dd>
+Compare this instance to another one.
 </dd>
 </dl>
 
@@ -266,7 +272,9 @@ as described above.
 The test program <code style="white-space: normal"><a target="test_no_rtti" href="../test/test_no_rtti.cpp">test_no_rtti</a></code>
 implements this function in terms of the <code style="white-space: normal"><a target="extended_type_info_no_rtti.hpp" href="../../../boost/serialization/extended_type_info_no_rtti.hpp">
 extended_type_info</a></code> API above to return the export key associated with the class.  
-This requires that non-abstract types be exported.
+This requires that non-abstract types be exported. It also demostrates the
+inter-operability with between two different implementations of
+<code style="white-space: normal">extended_type_info</code>.
 
 <hr>
 <p><i>&copy; Copyright <a href="http://www.rrsd.com">Robert Ramey</a> 2005. 
diff --git a/doc/serialization.html b/doc/serialization.html
index 32583287..4a47a3e1 100644
--- a/doc/serialization.html
+++ b/doc/serialization.html
@@ -54,6 +54,7 @@ http://www.boost.org/LICENSE_1_0.txt)
       <dt><a href="#derivedpointers">Pointers to Objects of Derived Classes</a>
       <dl class="page-index">
         <dt><a href="#registration">Registration</a>
+        <dt><a href="#export">Export</a>
         <dt><a href="#instantiation">Instantiation</a>
         <dt><a href="#selectivetracking">Selective Tracking</a>
         <dt><a href="#runtimecasting">Runtime Casting</a>
@@ -676,8 +677,9 @@ main(){
 Note that if the serialization function is split between save and load, both
 functions must include the registration.  This is required to keep the save
 and corresponding load in syncronization.
-<p>
-This will work but may be inconvenient.  We don't always know which derived
+
+<h4><a name="export">Export</a></h4>
+The above will work but may be inconvenient.  We don't always know which derived
 classes we are going to serialize when we write the code to serialize through
 a base class pointer.  Every time a new derived class is written we have to
 go back to all the places where the base class is serialized and update the
diff --git a/doc/special.html b/doc/special.html
index 3603d292..e2af918d 100644
--- a/doc/special.html
+++ b/doc/special.html
@@ -27,7 +27,6 @@ http://www.boost.org/LICENSE_1_0.txt)
 <hr>
 <dl class="page-index">
   <dt><a href="#objecttracking">Object Tracking</a>
-  <dt><a href="#export">Exporting Class Serialization</a>
   <dt><a href="#classinfo">Class Information</a>
   <dt><a href="#portability">Archive Portability</a>
   <dl class="page-index">
@@ -36,6 +35,7 @@ http://www.boost.org/LICENSE_1_0.txt)
   </dl>
   <dt><a href="#binary_archives">Binary Archives</a>
   <dt><a href="#xml_archives">XML Archives</a>
+  <dt><a href="#export">Exporting Class Serialization</a>
   <dt><a href="#dlls">DLLS - Serialization and Runtime Linking</a>
   <dt><a href="#multi_threading">Multi-Threading</a>
   <dt><a href="#optimizations">Optimizations</a>
@@ -153,63 +153,6 @@ redundant save/load operations.
 BOOST_CLASS_TRACKING(my_virtual_base_class, boost::serialization::track_always)
 </code></pre>
 
-<h3><a name="export">Exporting Class Serialization</a></h3>
-<a target="detail" href="traits.html#export">Elsewhere</a> in this manual, we have described 
-<code style="white-space: normal">BOOST_CLASS_EXPORT</code>. This is used to make the serialization library aware
-that code should be instantiated for serialization of a given class even though the
-class hasn't been otherwise referred to by the program.  This functionality
-is necessary to implement serialization of pointers through a virtual base
-class pointer.  That is, a polymorphic pointer.
-<p>
-This macro specifies a "<b>G</b>lobally <b>U</b>nique <b>ID</b>entifier".  
-This is an string which identifies the class to be created when data is loaded.
-Generally a text representation of the class name is sufficient for this purpose, 
-but in certain cases it maybe necessary to specify a different string by using 
-<code style="white-space: normal">BOOST_CLASS_EXPORT_GUID</code> 
-rather than a simple 
-<code style="white-space: normal">BOOST_CLASS_EXPORT</code>.
-
-<p>
-<code style="white-space: normal">BOOST_CLASS_EXPORT</code> would usually 
-be specified in the same header file as the class declaration to which it 
-corresponds.  That is, <code style="white-space: normal">BOOST_CLASS_EXPORT(T)</code>
-is a "trait" of the class T. So a program using this class will look 
-something like:
-
-<pre><code>
-#include &lt;boost/archive/xml_oarchive.hpp&gt;
-.... // any other archive classes
-#include "my_class.hpp"  // which contains BOOST_CLASS_EXPORT(my_class)
-</code></pre>
-
-These headers can be in any order.  (In boost versions 1.34
-and earlier, the archive headers had to go before any headers which
-contain <code style="white-space: normal">BOOST_CLASS_EXPORT</code>.)
-Any code required to serialize types specified
-by <code style="white-space: normal">BOOST_CLASS_EXPORT</code> will be
-instantiated for each archive whose header is included.  (note that the code 
-is instantiated regardless of whether or not it is actually invoked.) 
-If no archive headers are included - no code should be instantiated. 
-This will permit <code style="white-space: normal">BOOST_CLASS_EXPORT</code> 
-to be a permanent part of the <code style="white-space: normal">my_class.hpp</code> .
-
-<p>
-Strictly speaking, export should not be necessary if all pointer serialization
-occurs through the most derived class.  However, in order to detect
-what would be catastophic error, the library traps ALL serializations through
-a pointer to a polymorphic which are not exported or otherwise registered.
-So, in practice, be prepared to register or export all classes with one
-or more virtual functions which are serialized through a pointer. 
-
-<p>
-Note that the implementation of this functionality depends upon vendor
-specific extensions to the C++ language.  So, there is no guarenteed portability
-of programs which use this facility.  However, all C++ compilers which
-are tested with boost provide the required extensions.  The library
-includes the extra declarations required by each of these compilers.
-It's reasonable to expect that future C++ compilers will support
-these extensions or something equivalent.
-
 <h3><a name="classinfo">Class Information</a></h3>
 By default, for each class serialized, class information is written to the archive.
 This information includes version number, implementation level and tracking
@@ -294,7 +237,7 @@ struct my_wrapper {
 class my_class {
     wchar_t a;
     short unsigned b;
-    template<&lt;class Archive&gt;
+    template&lt;class Archive&gt;
     Archive & serialize(Archive & ar, unsigned int version){
         ar & my_wrapper(a);
         ar & my_wrapper(b);
@@ -353,13 +296,105 @@ just the value portion of the data is serialized. The name portion is discarded
 So by always using <a target="detail" href="wrappers.html#nvp">name-value pairs</a>, it will
 be guarenteed that all data can be serialized to all archive classes with maximum efficiency.
 
+<h3><a name="export">Exporting Class Serialization</a></h3>
+<a target="detail" href="traits.html#export">Elsewhere</a> in this manual, we have described 
+<code style="white-space: normal">BOOST_CLASS_EXPORT</code>. 
+Export implies two things:
+<ul>
+<li>Instantiates code which is not otherwise referred to.
+<li>Associates an external identifier with the class to be serialized.
+The fact that the class isn't explicitly referred to implies this
+requirement.
+</ul>
+In C++, usage of code not explicitly referred to is implemented via
+virtual functions.  Hence, the need for export is implied by the 
+usage of a derived class that is manipulated via a pointer or
+reference to it's base class.
+
+<p>
+<code style="white-space: normal">BOOST_CLASS_EXPORT</code> in the same
+source module that includes any of the archive class headers will
+instantiate code required to serialize polymorphic pointers of
+the indicated type to the all those archive classes. If no
+archive class headers are included, then no code will be instantiated.
+
+<p>
+Note that the implemenation of this functionality requires
+that the <code style="white-space: normal">BOOST_CLASS_EXPORT</code>
+macro appear <b>after</b> and the inclusion of any archive
+class headers for which code is to be instantiated.
+So, code that uses <code style="white-space: normal">BOOST_CLASS_EXPORT</code>
+will look like the following:
+<pre><code>
+#include &lt;boost/archive/text_oarchive.hpp&gt;
+#include &lt;boost/archive/text_oarchive.hpp&gt;
+... // other archives
+
+#include "a.hpp" // header declaration for class a
+BOOST_CLASS_EXPORT(a)
+... // other class headers and exports
+</code></pre>
+This will be true regardless of whether the is part
+of a stand alone executable, a static library or
+a dyanmic or shared library.  
+<p>
+Note that including
+<code style="white-space: normal">BOOST_CLASS_EXPORT</code>
+in the "a.hpp" header itself as one would do with
+other serialization traits will make it difficult
+or impossible to follow the rule above regarding
+inclusion of archive headers before
+<code style="white-space: normal">BOOST_CLASS_EXPORT</code>
+is invoked.  This is different than other serialization
+traits which would normally be included in same file
+as the class declaration.
+
+<p>
+This system has certain implications for placing code in static or shared
+libraries.  Placing <code style="white-space: normal">BOOST_CLASS_EXPORT</code>
+in library code will have no effect unless archive class headers are
+also included.  So when building a library, one should include all headers
+for all the archive classes which he anticipates using. Alternatively,
+one can include headers for just the
+<a href="archive_reference.html#polymorphic">Polymoprhic Archives</a>.
+Also, when making shared libraries, there is currently a restriction
+that only one such library can use <code style="white-space: normal">BOOST_CLASS_EXPORT</code>
+for any given type. All this will most likely make it inconvenient
+to include <code style="white-space: normal">BOOST_CLASS_EXPORT</code>
+as part of the header of the class to be serialized.  In this case
+it would probably be best to include it in source module which
+implements the class.
+
+<p>
+Strictly speaking, export should not be necessary if all pointer serialization
+occurs through the most derived class.  However, in order to detect
+what would be catastophic error, the library traps ALL serializations through
+a pointer to a polymorphic which are not exported or otherwise registered.
+So, in practice, be prepared to register or export all classes with one
+or more virtual functions which are serialized through a pointer. 
+
+<p>
+Note that the implementation of this functionality depends upon vendor
+specific extensions to the C++ language.  So, there is no guarenteed portability
+of programs which use this facility.  However, all C++ compilers which
+are tested with boost provide the required extensions.  The library
+includes the extra declarations required by each of these compilers.
+It's reasonable to expect that future C++ compilers will support
+these extensions or something equivalent.
+
 <h3><a name="dlls">DLLS - Serialization and Runtime Linking</a></h3>
 Serialization code can be placed in libraries to be linked at runtime.  That is,
-code can be placed in DLLS(Windows) or Shared Libraries(*nix).  
-Along with the "export" facility, this
-permits a program to written without knowledge of the actual types to be serialized.
-This package doesn't include an example of this technique - but coding would be
-very similar to the example 
+code can be placed in DLLS(Windows) Shared Libraries(*nix), or static libraries
+as well as the main executable.  As long as
+
+<a target="detail" href="serialization.html#export">
+<code style="white-space: normal">BOOST_CLASS_EXPORT</code>
+</a>
+
+is not used, The serialization library imposes no special requirements
+that need be taken into account when distributing code among various modules.
+<p>
+For static libraries, this is illustrated by
 <a href = "../example/demo_pimpl.cpp" target="demo_pimpl">
 <code style="white-space: normal">demo_pimpl.cpp</code>
 </a>,
@@ -370,52 +405,55 @@ and
 <a href = "../example/demo_pimpl_A.hpp" target="demo_pimpl">
 <code style="white-space: normal">demo_pimpl_A.hpp</code>
 </a>
-where implementation of serializaton is completely separate
-from the main program.
+where implementation of serializaton is in a static library 
+completely separate from the main program.
+
+<p>
+For runtime linked libraries this is illustrated by one of the tests:
+
+<a href = "../test/test_dll_simple.cpp" target="test_dll_simple">
+<code style="white-space: normal">test_dll_simple</code>
+</a>,
+and
+<a href = "../test/dll_A.cpp" target="dll_A">
+<code style="white-space: normal">dll_A.cpp</code>
+</a>
+where implementation of serializaton is also completely separate
+from the main program but the code is loaded at runtime.  In this
+example, this code is loaded automatically when the program which
+uses it starts up, but it could just as well be loaded and unloaded 
+with an OS dependent API call.
 
 <h3><a name="multi_threading">Multi-Threading</a></h3>
-The nature of serialization would conflict with multiple thread concurrently
-writing/reading from/to a single open archive.  Since each archive is
-independent from ever other one, there should be no problem
-in having multiple open archives from one or more threads.
+The fundamental purpose of serialization would conflict with multiple 
+thread concurrently writing/reading from/to a single open archive instance.
+The library implementation presumes that the application avoids such an situtation.
 <p>
-Well, not quite.
+However, Writing/Reading different archives simultaneously
+in different tasks is permitted as each archive instance is (almost) 
+completely independent from any other archive instance.  The only shared 
+information are some type tables which have been implemented using a 
+lock-free thread-safe 
+<a target="detail" href="singleton.html">
+<code style="white-space: normal">singleton</code>
+</a>
+described elsewhere in this documentation.
 <p>
-There are a couple of global data structures for holding
-information of serializable types.  These structures are
-used to dispatch to correct code to handle each pair
-of serializable types and archive types.  Since this
-information is shared among all archives, there is 
-potential for problems.  This has been addressed
-carefully implementing the library so that these 
-structures are all initialized before 
-<code style="white-space: normal">main(...)</code>
-is called.  From then on they are never altered.  So
-there SHOULD be no problem having mulitple archives
-open simultaneously - be it from the same or different
-threads.
-<p>
-Well, almost.
-<p>
-With dynamically loaded code - DLLS or Shared Libraries, 
-these global data structures can be altered when a library
-is loaded or unloaded.  That is, in this case, these
-globa data structures can be altered after 
-<code style="white-space: normal">main(...)</code>
-is called.  So if a thread is dynamically loading/unloading
-modules which contain serialization code while an 
-archive is open there could be problems.  Also, if
-such loading/unloading is happening concurrently
-in different threads, there could also be problems.
-<p>
-It might not be easy to control this.  Is possible that
-some systems may not actually load modules until they
-are actually needed.  So even though we think that
-there is not dynamic loading/unloading of such code
-it could be occurring as "help" to manage resources.
-On such systems, access to archive code would have 
-to be syncronized with some multi-threading construct
-in order to be functional.
+This singleton implemenation guarentees that all of this shared
+information is initialized when the code module which contains
+them is loaded.  The serialization library takes care to
+ensure that these data structures are not subsequently
+modified. The only time there could be a problem would
+be if code is loaded/unloaded while another task is
+serializing data.  This could only occur for types whose 
+serialization is implemented in a dynamically loaded/unload DLL
+or shared library.  So if the following is avoided:
+<ul>
+    <li>Accessing the same archive instance from different tasks.
+    <li>Loading/Unloading DLLS or shared libraries while any archive
+    instances are open.
+</ul>
+The library should be thread safe.
 
 <h3><a name="optimizations">Optimizations</a></h3>
 In performance critical applications that serialize large sets of contiguous data of homogeneous
diff --git a/doc/void_cast.html b/doc/void_cast.html
index 190964eb..51c0bae3 100644
--- a/doc/void_cast.html
+++ b/doc/void_cast.html
@@ -44,8 +44,8 @@ They are declared in the namespace
 template&lt;class Derived, class Base&gt;
 const void_cast_detail::void_caster &
 void_cast_register(
-    const Derived * derived = NULL, 
-    const Base * base = NULL
+    Derived const * derived = NULL, 
+    Base * const base = NULL
 )
 </code></pre></h4></dt>
 <dd>