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| <font size="6" face="Verdana, Arial, Helvetica, sans-serif"><b>Policies</b></font> |
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| <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> |
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| |
| <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. |
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| 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. |
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| <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> |
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