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Move joel's updates over from the main trunk (finish)
[SVN r15870]
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Dave Abrahams
@@ -142,7 +142,7 @@ or more policies can be composed by chaining. Here's the general syntax:</p>
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</span></pre></code>
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<p>
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Here is the list of predefined call policies. A complete reference detailing
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these can be found <a href="../../v2/CallPolicies.html">
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these can be found <a href="../../v2/reference.html#models_of_call_policies">
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here</a>.</p>
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<ul><li><b>with_custodian_and_ward</b><br> Ties lifetimes of the arguments</li><li><b>with_custodian_and_ward_postcall</b><br> Ties lifetimes of the arguments and results</li><li><b>return_internal_reference</b><br> Ties lifetime of one argument to that of result</li><li><b>return_value_policy<T> with T one of:</b><br></li><li><b>reference_existing_object</b><br>naïve (dangerous) approach</li><li><b>copy_const_reference</b><br>Boost.Python v1 approach</li><li><b>copy_non_const_reference</b><br></li><li><b>manage_new_object</b><br> Adopt a pointer and hold the instance</li></ul><table width="80%" border="0" align="center">
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<tr>
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@@ -56,12 +56,11 @@ Then, in Python:</p>
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Note that <tt>name</tt> is exposed as <b>read-only</b> while <tt>value</tt> is exposed
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as <b>read-write</b>.</p>
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<code><pre>
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<span class=special>>>> </span><span class=identifier>x</span><span class=special>.</span><span class=identifier>name </span><span class=special>= </span><span class=literal>'e' </span>#<span class=identifier>can</span><span class=literal>'t change name
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>>> x.name = 'e' # can't change name
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Traceback (most recent call last):
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File "<stdin>", line 1, in ?
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AttributeError: can'</span><span class=identifier>t </span><span class=identifier>set </span><span class=identifier>attribute
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</span></pre></code>
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<table border="0">
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AttributeError: can't set attribute
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</pre></code><table border="0">
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<tr>
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<td width="30"><a href="../index.html"><img src="theme/u_arr.gif" border="0"></a></td>
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<td width="30"><a href="constructors.html"><img src="theme/l_arr.gif" border="0"></a></td>
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@@ -92,15 +92,16 @@ polymorphically <i>from</i> <b>C++</b>. </td>
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<p>
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Wrapping <tt>Base</tt> and the free function <tt>call_f</tt>:</p>
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<code><pre>
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<span class=identifier>class_</span><span class=special><</span><span class=identifier>Base</span><span class=special>, </span><span class=identifier>BaseWrap</span><span class=special>, </span><span class=identifier>noncopyable</span><span class=special>>(</span><span class=string>"Base"</span><span class=special>, </span><span class=identifier>no_init</span><span class=special>)
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<span class=identifier>class_</span><span class=special><</span><span class=identifier>Base</span><span class=special>, </span><span class=identifier>BaseWrap</span><span class=special>, </span><span class=identifier>boost</span><span class=special>::</span><span class=identifier>noncopyable</span><span class=special>>(</span><span class=string>"Base"</span><span class=special>, </span><span class=identifier>no_init</span><span class=special>)
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</span><span class=special>;
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</span><span class=identifier>def</span><span class=special>(</span><span class=string>"call_f"</span><span class=special>, </span><span class=identifier>call_f</span><span class=special>);
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</span></pre></code>
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<p>
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Notice that we parameterized the <tt>class_</tt> template with <tt>BaseWrap</tt> as the
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second parameter. What is <tt>noncopyable</tt>? Without it, the library will try
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to instantiate a copy constructor for returning Base objects from
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functions.</p>
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to create code for converting Base return values of wrapped functions to
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Python. To do that, it needs Base's copy constructor... which isn't
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available, since Base is an abstract class.</p>
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<p>
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In Python, let us try to instantiate our <tt>Base</tt> class:</p>
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<code><pre>
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@@ -64,7 +64,7 @@ expose instead.</p>
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<p>
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<tt>init<std::string>()</tt> exposes the constructor taking in a
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<tt>std::string</tt> (in Python, constructors are spelled
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"<tt>__init__(...)</tt>").</p>
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"<tt>"__init__"</tt>").</p>
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<p>
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We can expose additional constructors by passing more <tt>init<...></tt>s to
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the <tt>def()</tt> member function. Say for example we have another World
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@@ -70,18 +70,21 @@ member functions.</p>
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<p>
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Demonstrates that you can write the C++ equivalent of <tt>"format" % x,y,z</tt>
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in Python, which is useful since there's no easy way to do that in std C++.</p>
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<table width="80%" border="0" align="center">
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<tr>
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<td class="note_box">
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<img src="theme/alert.gif"></img> Beware the common pitfall of
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forgetting that the constructors of most of Python's mutable types
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make copies, just as in Python.<br><br>
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<tt>dict d(x.attr("__dict__")); # makes a copy of x's dict<br>
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d['whatever'] = 3; # modifies a copy of x.__dict__ (not the original)<br></tt>
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</td>
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</tr>
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</table>
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<p>
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<img src="theme/alert.gif"></img> <b>Beware</b> the common pitfall of forgetting that the constructors
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of most of Python's mutable types make copies, just as in Python.</p>
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<p>
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Python:</p>
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<code><pre>
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<span class=special>>>> </span><span class=identifier>d </span><span class=special>= </span><span class=identifier>dict</span><span class=special>(</span><span class=identifier>x</span><span class=special>.</span><span class=identifier>__dict__</span><span class=special>) </span>#<span class=identifier>copies </span><span class=identifier>x</span><span class=special>.</span><span class=identifier>__dict__
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</span><span class=special>>>> </span><span class=identifier>d</span><span class=special>[</span><span class=literal>'whatever'</span><span class=special>] </span>#<span class=identifier>modifies </span><span class=identifier>the </span><span class=identifier>copy
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</span></pre></code>
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<p>
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C++:</p>
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<code><pre>
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<span class=identifier>dict </span><span class=identifier>d</span><span class=special>(</span><span class=identifier>x</span><span class=special>.</span><span class=identifier>attr</span><span class=special>(</span><span class=string>"__dict__"</span><span class=special>)); </span>#<span class=identifier>copies </span><span class=identifier>x</span><span class=special>.</span><span class=identifier>__dict__
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</span><span class=identifier>d</span><span class=special>[</span><span class=literal>'whatever'</span><span class=special>] </span><span class=special>= </span><span class=number>3</span><span class=special>; </span>#<span class=identifier>modifies </span><span class=identifier>the </span><span class=identifier>copy
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</span></pre></code>
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<a name="class__lt_t_gt__as_objects"></a><h2>class_<T> as objects</h2><p>
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Due to the dynamic nature of Boost.Python objects, any <tt>class_<T></tt> may
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also be one of these types! The following code snippet wraps the class
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@@ -39,31 +39,29 @@
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Grosse-Kunstleve</a> implemented the <a href="pickle.html">pickle
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support</a>, and has enthusiastically supported the library since its
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birth, contributing to design decisions and providing invaluable
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real-world insight into user requirements. Ralf has written some
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<a href="faq.html#question2">extensions</a> for converting C++ containers that I hope will be incorporated
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into the library soon. He also implemented the cross-module support in
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the first version of Boost.Python. More importantly, Ralf makes sure
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nobody forgets the near-perfect synergy of C++ and Python for solving the
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problems of large-scale software construction.</p>
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real-world insight into user requirements. Ralf has written some <a href=
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"faq.html#question2">extensions</a> for converting C++ containers that I
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hope will be incorporated into the library soon. He also implemented the
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cross-module support in the first version of Boost.Python. More
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importantly, Ralf makes sure nobody forgets the near-perfect synergy of
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C++ and Python for solving the problems of large-scale software
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construction.</p>
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<p><a href="../../../../people/aleksey_gurtovoy.htm">Aleksey
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Gurtovoy</a> wrote an incredible C++ <a
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href="http://www.mywikinet.com/mpl">Template Metaprogramming
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Library</a> which allows Boost.Python to perform much of its
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compile-time magic. In addition, Aleksey very generously
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contributed his time and deep knowledge of the quirks of various
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buggy compilers to help us get around problems at crucial moments.
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<p><a href="../../../../people/aleksey_gurtovoy.htm">Aleksey Gurtovoy</a>
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wrote an incredible C++ <a href="http://www.mywikinet.com/mpl">Template
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Metaprogramming Library</a> which allows Boost.Python to perform much of
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its compile-time magic. In addition, Aleksey very generously contributed
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his time and deep knowledge of the quirks of various buggy compilers to
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help us get around problems at crucial moments.</p>
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<p><a href="../../../../people/paul_mensonides.htm">Paul
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Mensonides</a>, building on the work <a
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href="../../../../people/vesa_karvonen.htm">Vesa Karvonen</a>,
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wrote a similarly amazing <a
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href="../../../preprocessor/doc/index.html">Preprocessor Metaprogramming
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Library</a>, and generously contributed the time and expertise to
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get it working in the Boost.Python library, rewriting much of
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Boost.Python to use the new preproccessor metaprogramming
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constructs and helping us to work around buggy and slow C++
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preprocessors.
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<p><a href="../../../../people/paul_mensonides.htm">Paul Mensonides</a>,
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building on the work <a href="../../../../people/vesa_karvonen.htm">Vesa
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Karvonen</a>, wrote a similarly amazing <a href=
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"../../../preprocessor/doc/index.html">Preprocessor Metaprogramming
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Library</a>, and generously contributed the time and expertise to get it
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working in the Boost.Python library, rewriting much of Boost.Python to
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use the new preproccessor metaprogramming constructs and helping us to
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work around buggy and slow C++ preprocessors.</p>
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<p><a href="mailto:achim@procoders.net">Achim Domma</a> contributed some
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of the <a href="reference.html#object_wrappers">Object Wrappers</a> and
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