[Boost-commit] svn:boost r71531 - sandbox/mutual_ptr/libs/smart_ptr/doc

Subject: [Boost-commit] svn:boost r71531 - sandbox/mutual_ptr/libs/smart_ptr/doc
From: phil_at_[hidden]
Date: 2011-04-26 21:46:44

Author: pbouchard
Date: 2011-04-26 21:46:43 EDT (Tue, 26 Apr 2011)
New Revision: 71531
URL: http://svn.boost.org/trac/boost/changeset/71531

Log:
* Added caveat to the tutorial
Text files modified: 
   sandbox/mutual_ptr/libs/smart_ptr/doc/tutorial.html |    29 +++++++++++++++++++++++++++++           
   1 files changed, 29 insertions(+), 0 deletions(-)

Modified: sandbox/mutual_ptr/libs/smart_ptr/doc/tutorial.html
==============================================================================
--- sandbox/mutual_ptr/libs/smart_ptr/doc/tutorial.html	(original)
+++ sandbox/mutual_ptr/libs/smart_ptr/doc/tutorial.html	2011-04-26 21:46:43 EDT (Tue, 26 Apr 2011)
@@ -61,6 +61,8 @@
     <dt>Basic</dt>
 
     <dt>Advanced</dt>
+
+    <dt>Caveat</dt>
   </dl>
 
   <h2><a name="basic" id="basic"></a>Basic</h2>
@@ -96,6 +98,33 @@
   c.push_back(new mutual&#60;int&#62;(11));
   </pre>
 
+  <h2><a name="caveat" id="caveat"></a>Caveat</h2>
+  
+  <p>Hierarchies with multiple inheritance without virtual tables will cause undefined behavior if a pointer to a derived class is assigned to a pointer of one 
+  of its base class.  For example:</p>
+
+  <pre>  
+  struct M { int i; };
+  struct N { int i; };
+  struct O : N, M { int i; };
+
+  mutual_ptr&#60;O&#62; po = new mutual&#60;O&#62;;
+  mutual_ptr&#60;N&#62; pn = po; // incorrect
+  mutual_ptr&#60;M&#62; pm = po; // incorrect
+  </pre>
+  
+  <p>A way to bypass any problem that might be created by the example above is to add virtual destructors to the classes:</p>
+
+  <pre>  
+  struct M { int i; virtual ~M() {} };
+  struct N { int i; virtual ~N() {} };
+  struct O : N, M { int i; };
+
+  mutual_ptr&#60;O&#62; po = new mutual&#60;O&#62;;
+  mutual_ptr&#60;N&#62; pn = po; // correct
+  mutual_ptr&#60;M&#62; pm = po; // correct
+  </pre>
+
   <hr>
 
   <p><a href="http://validator.w3.org/check?uri=referer"><img border="0" src=