<html> <head> <!-- Generated by the Spirit (http://spirit.sf.net) QuickDoc --> <title>Policies</title> <link rel="stylesheet" href="theme/style.css" type="text/css"> <link rel="prev" href="renaming_and_excluding.html"> <link rel="next" href="templates.html"> </head> <body> <table width="100%" height="48" border="0" cellspacing="2"> <tr> <td><img src="../../../../boost.png"> </td> <td width="85%"> <font size="6" face="Verdana, Arial, Helvetica, sans-serif"><b>Policies</b></font> </td> </tr> </table> <br> <table border="0"> <tr> <td width="30"><a href="../index.html"><img src="theme/u_arr.gif" border="0"></a></td> <td width="30"><a href="renaming_and_excluding.html"><img src="theme/l_arr.gif" border="0"></a></td> <td width="20"><a href="templates.html"><img src="theme/r_arr.gif" border="0"></a></td> </tr> </table> <p> Even thought Pyste can identify various elements in the C++ code, like virtual member functions, attributes, and so on, one thing that it can't do is to guess the semantics of functions that return pointers or references. In this case, the user must manually specify the policy. Policies are explained in the <a href="../../doc/tutorial/doc/html/python/functions.html#python.call_policies"> tutorial</a>.</p> <p> The policies in Pyste are named exactly as in <a href="../../index.html"> Boost.Python</a>, only the syntax is slightly different. For instance, this policy:</p> <code><pre> <span class=identifier>return_internal_reference</span><span class=special><</span><span class=number>1</span><span class=special>, </span><span class=identifier>with_custodian_and_ward</span><span class=special><</span><span class=number>1</span><span class=special>, </span><span class=number>2</span><span class=special>> >() </span></pre></code> <p> becomes in Pyste: </p> <code><pre> <span class=identifier>return_internal_reference</span><span class=special>(</span><span class=number>1</span><span class=special>, </span><span class=identifier>with_custodian_and_ward</span><span class=special>(</span><span class=number>1</span><span class=special>, </span><span class=number>2</span><span class=special>)) </span></pre></code> <p> The user can specify policies for functions and virtual member functions with the <tt>set_policy</tt> function:</p> <code><pre> <span class=identifier>set_policy</span><span class=special>(</span><span class=identifier>f</span><span class=special>, </span><span class=identifier>return_internal_reference</span><span class=special>()) </span><span class=identifier>set_policy</span><span class=special>(</span><span class=identifier>C</span><span class=special>.</span><span class=identifier>foo</span><span class=special>, </span><span class=identifier>return_value_policy</span><span class=special>(</span><span class=identifier>manage_new_object</span><span class=special>)) </span></pre></code> <table width="80%" border="0" align="center"> <tr> <td class="note_box"> <img src="theme/note.gif"></img> <b>What if a function or member function needs a policy and the user doesn't set one?</b><br><br> If a function needs a policy and one was not set, Pyste will issue a error. The user should then go in the interface file and set the policy for it, otherwise the generated cpp won't compile. </td> </tr> </table> <table width="80%" border="0" align="center"> <tr> <td class="note_box"> <img src="theme/note.gif"></img> Note that for functions that return <tt>const T&</tt>, the policy <tt>return_value_policy<copy_const_reference>()</tt> wil be used by default, because that's normally what you want. You can change it to something else if you need to, though. </td> </tr> </table> <table border="0"> <tr> <td width="30"><a href="../index.html"><img src="theme/u_arr.gif" border="0"></a></td> <td width="30"><a href="renaming_and_excluding.html"><img src="theme/l_arr.gif" border="0"></a></td> <td width="20"><a href="templates.html"><img src="theme/r_arr.gif" border="0"></a></td> </tr> </table> <br> <hr size="1"><p class="copyright">Copyright © 2003 Bruno da Silva de Oliveira<br>Copyright © 2002-2003 Joel de Guzman<br><br> <font size="2">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) </font> </p> </body> </html>