*** empty log message ***

[SVN r33671]
2026-02-27 05:12:11 +00:00 · 2006-04-11 21:17:33 +00:00
parent d2ea264db8
commit 90fe122a82
4 changed files with 137 additions and 9 deletions
--- a/doc/guidelines.html
+++ b/doc/guidelines.html
@@ -290,6 +290,8 @@ ul.auto-toc {
 <div class="document" id="boost-pointer-container-library">
 <h1 class="title"><img alt="Boost" src="boost.png" /> Pointer Container Library</h1>
 <h2 class="subtitle" id="usage-guidelines">Usage Guidelines</h2>
+<div class="section">
+<h1><a id="choosing-the-right-container" name="choosing-the-right-container">Choosing the right container</a></h1>
 <p>The recommended usage pattern of the container classes are the same as the 
 for normal standard containers.</p>
 <p><tt class="docutils literal"><span class="pre">ptr_vector</span></tt>, <tt class="docutils literal"><span class="pre">ptr_list</span></tt> and <tt class="docutils literal"><span class="pre">ptr_deque</span></tt> offer the programmer different 
@@ -306,6 +308,60 @@ one element for each key. Otherwise, it supports equivalent keys.
 <tt class="docutils literal"><span class="pre">ptr_set</span></tt> and <tt class="docutils literal"><span class="pre">ptr_map</span></tt> support unique keys.  
 <tt class="docutils literal"><span class="pre">ptr_multiset</span></tt> and <tt class="docutils literal"><span class="pre">ptr_multimap</span></tt> 
 support equivalent keys.</p>
+</div>
+<div class="section">
+<h1><a id="recommended-practice-for-object-oriented-programming" name="recommended-practice-for-object-oriented-programming">Recommended practice for Object-Oriented Programming</a></h1>
+<p>Idiomtic Object-Oriented Programming in C++ looks a bit different from 
+the way it is done in other languages. This is partly because C++ 
+has both value and reference semantics, and partly because C++ is more flexible
+than other languages. Below is a list of recommendations that you are
+encouraged to follow:</p>
+<div class="section">
+<h2><a id="make-base-classes-abstract-and-without-data" name="make-base-classes-abstract-and-without-data">1. Make base classes abstract and without data</a></h2>
+<p>The has the following advantages:</p>
+<blockquote>
+<ol class="loweralpha simple">
+<li>It reduces <em>coupling</em> because you do not have to maintain or update state</li>
+</ol>
+<!--  -->
+<ol class="loweralpha simple" start="2">
+<li>It helps you to avoid <em>slicing</em></li>
+</ol>
+<!--  -->
+<ol class="loweralpha simple" start="3">
+<li>It ensures you <em>override</em> the right function</li>
+</ol>
+</blockquote>
+<p>You might also want to read the following articles:</p>
+<ul class="simple">
+<li>Kevlin Henney's <a class="reference" href="http://www.two-sdg.demon.co.uk/curbralan/papers/SixOfTheBest.pdf">Six of the best</a></li>
+</ul>
+<ul class="simple">
+<li>Jack Reeves' <a class="reference" href="http://www.ddj.com/documents/s=10011/q=1/cuj0602reeves/0602reeves.html">Multiple Inheritance Considered Useful</a></li>
+</ul>
+</div>
+<div class="section">
+<h2><a id="make-virtual-functions-private-and-provide-a-non-virtual-public-forwarding-function" name="make-virtual-functions-private-and-provide-a-non-virtual-public-forwarding-function">2. Make virtual functions private and provide a non-virtual public forwarding function</a></h2>
+<p>This has the following advantages:</p>
+<blockquote>
+<ol class="loweralpha simple">
+<li>It makes sure all calls to the virtual function always goes through one place in your code</li>
+</ol>
+<!--  -->
+<ol class="loweralpha simple" start="2">
+<li>It enables you to check preconditions and postconditions inside the forwarding function</li>
+</ol>
+</blockquote>
+<p>You might also want to read Herb Sutter's article <a class="reference" href="http://www.gotw.ca/publications/mill18.htm">Virtuality</a>.</p>
+</div>
+<div class="section">
+<h2><a id="derive-your-base-class-from-boost-noncopyable" name="derive-your-base-class-from-boost-noncopyable">3. Derive your base class from <tt class="docutils literal"><span class="pre">boost::noncopyable</span></tt></a></h2>
+<p>Having an abstact base class prevents slicing when the base class is involved, but
+it does not prevent it for classes further down the hierarchy. This is where
+<a class="reference" href="http://www.boost.org/libs/utility/utility.htm#Class_noncopyable">boost::noncopyable</a> is handy to use.</p>
+</div>
+<div class="section">
+<h2><a id="don-t-allow-nulls-if-you-can-avoid-it-null-object" name="don-t-allow-nulls-if-you-can-avoid-it-null-object">4. don't allow nulls if you can avoid it, Null Object</a></h2>
 <p><strong>Navigate:</strong></p>
 <ul class="simple">
 <li><a class="reference" href="ptr_container.html">home</a></li>
@@ -320,5 +376,7 @@ support equivalent keys.</p>
 </tbody>
 </table>
 </div>
+</div>
+</div>
 </body>
 </html>
--- a/doc/guidelines.rst
+++ b/doc/guidelines.rst
@@ -8,6 +8,9 @@
 Usage Guidelines
 ================

+Choosing the right container
+----------------------------
+
 The recommended usage pattern of the container classes are the same as the 
 for normal standard containers.  

@@ -27,6 +30,71 @@ one element for each key. Otherwise, it supports equivalent keys.
 ``ptr_multiset`` and ``ptr_multimap`` 
 support equivalent keys.  

+Recommended practice for Object-Oriented Programming
+----------------------------------------------------
+
+Idiomtic Object-Oriented Programming in C++ looks a bit different from 
+the way it is done in other languages. This is partly because C++ 
+has both value and reference semantics, and partly because C++ is more flexible
+than other languages. Below is a list of recommendations that you are
+encouraged to follow:
+
+1. Make base classes abstract and without data
++++++++++++++++++++++++++++++++++++++++++++++
+
+The has the following advantages:
+
+	a. It reduces *coupling* because you do not have to maintain or update state
+
+	..
+		
+        b. It helps you to avoid *slicing*
+	
+	..
+	
+        c. It ensures you *override* the right function
+
+You might also want to read the following articles:
+
+- Kevlin Henney's `Six of the best`__
+
+.. __: http://www.two-sdg.demon.co.uk/curbralan/papers/SixOfTheBest.pdf
+
+- Jack Reeves' `Multiple Inheritance Considered Useful`__
+
+.. __: http://www.ddj.com/documents/s=10011/q=1/cuj0602reeves/0602reeves.html
+
+  
+2. Make virtual functions private and provide a non-virtual public forwarding function
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+
+This has the following advantages:
+
+	a. It makes sure all calls to the virtual function always goes through one place in your code
+	
+	..
+	
+	b. It enables you to check preconditions and postconditions inside the forwarding function
+
+You might also want to read Herb Sutter's article `Virtuality`__.
+
+.. __: http://www.gotw.ca/publications/mill18.htm
+
+3. Derive your base class from ``boost::noncopyable``
+++++++++++++++++++++++++++++++++++++++++++++++++++++
+
+Having an abstact base class prevents slicing when the base class is involved, but
+it does not prevent it for classes further down the hierarchy. This is where
+`boost::noncopyable`__ is handy to use.
+
+.. __ : http://www.boost.org/libs/utility/utility.htm#Class_noncopyable
+
+
+
+4. don't allow nulls if you can avoid it, Null Object
++++++++++++++++++++++++++++++++++++++++++++++++++++++
+
+
 **Navigate:**

 - `home <ptr_container.html>`_
--- a/doc/reference.html
+++ b/doc/reference.html
@@ -333,7 +333,6 @@ the <a class="reference" href="reference.html#the-clone-allocator-concept">Clone
 <h1><a id="the-clonable-concept" name="the-clonable-concept">The Clonable concept</a></h1>
 <p><strong>Refinement of</strong></p>
 <ul class="simple">
-<li>Copy Constructible</li>
 <li>Heap Allocable</li>
 <li>Heap Deallocable</li>
 </ul>
@@ -365,22 +364,26 @@ the containers does not even require the stored type to be Clonable.</p>
 <p><strong>Valid expressions</strong></p>
 <table border="1" class="docutils">
 <colgroup>
-<col width="24%" />
-<col width="18%" />
-<col width="58%" />
+<col width="19%" />
+<col width="14%" />
+<col width="46%" />
+<col width="20%" />
 </colgroup>
 <tbody valign="top">
 <tr><td><strong>Expression</strong></td>
 <td><strong>Type</strong></td>
 <td><strong>Semantics</strong></td>
+<td><strong>Postcondition</strong></td>
 </tr>
 <tr><td><tt class="docutils literal"><span class="pre">new_clone(a);</span></tt></td>
 <td><tt class="docutils literal"><span class="pre">T*</span></tt></td>
 <td>Allocate a new object that can be considered equivalent to the <tt class="docutils literal"><span class="pre">a</span></tt> object</td>
+<td><tt class="docutils literal"><span class="pre">typeid(new_clone(a))</span> <span class="pre">==</span> <span class="pre">typeid(a)</span></tt></td>
 </tr>
 <tr><td><tt class="docutils literal"><span class="pre">delete_clone(ptr);</span></tt></td>
 <td><tt class="docutils literal"><span class="pre">void</span></tt></td>
 <td>Deallocate an object previously allocated with <tt class="docutils literal"><span class="pre">allocate_clone()</span></tt>. Must not throw</td>
+<td>&nbsp;</td>
 </tr>
 </tbody>
 </table>
--- a/doc/reference.rst
+++ b/doc/reference.rst
@@ -52,7 +52,6 @@ The Clonable concept

 **Refinement of**

- Copy Constructible
 - Heap Allocable
 - Heap Deallocable

@@ -70,11 +69,11 @@ the containers does not even require the stored type to be Clonable.
       
 **Valid expressions**

-===================================== =========================== ========================================================================================
-     **Expression**                          **Type**                  **Semantics**
-   ``new_clone(a);``                         ``T*``                  Allocate a new object that can be considered equivalent to the ``a`` object
+===================================== =========================== ======================================================================================== ===================================
+     **Expression**                          **Type**                  **Semantics**                                                                        **Postcondition**
+   ``new_clone(a);``                         ``T*``                  Allocate a new object that can be considered equivalent to the ``a`` object            ``typeid(new_clone(a)) == typeid(a)``
   ``delete_clone(ptr);``                    ``void``                Deallocate an object previously allocated with ``allocate_clone()``. Must not throw 
-===================================== =========================== ========================================================================================
+===================================== =========================== ======================================================================================== ===================================


 Default implementation