<html> <head> <!-- Generated by the Spirit (http://spirit.sf.net) QuickDoc --> <title>Templates</title> <link rel="stylesheet" href="theme/style.css" type="text/css"> <link rel="prev" href="policies.html"> <link rel="next" href="wrappers.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>Templates</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="policies.html"><img src="theme/l_arr.gif" border="0"></a></td> <td width="20"><a href="wrappers.html"><img src="theme/r_arr.gif" border="0"></a></td> </tr> </table> <p> Template classes can easily be exported too, but you can't export the template itself... you have to export instantiations of it! So, if you want to export a <tt>std::vector</tt>, you will have to export vectors of int, doubles, etc.</p> <p> Suppose we have this code:</p> <code><pre> <span class=keyword>template </span><span class=special><</span><span class=keyword>class </span><span class=identifier>T</span><span class=special>> </span><span class=keyword>struct </span><span class=identifier>Point </span><span class=special>{ </span><span class=identifier>T </span><span class=identifier>x</span><span class=special>; </span><span class=identifier>T </span><span class=identifier>y</span><span class=special>; }; </span></pre></code> <p> And we want to export <tt>Point</tt>s of int and double:</p> <code><pre> <span class=identifier>Point </span><span class=special>= </span><span class=identifier>Template</span><span class=special>(</span><span class=string>"Point"</span><span class=special>, </span><span class=string>"point.h"</span><span class=special>) </span><span class=identifier>Point</span><span class=special>(</span><span class=string>"int"</span><span class=special>) </span><span class=identifier>Point</span><span class=special>(</span><span class=string>"double"</span><span class=special>) </span></pre></code> <p> Pyste will assign default names for each instantiation. In this example, those would be "<tt>Point_int</tt>" and "<tt>Point_double</tt>", but most of the time users will want to rename the instantiations:</p> <code><pre> <span class=identifier>Point</span><span class=special>(</span><span class=string>"int"</span><span class=special>, </span><span class=string>"IPoint"</span><span class=special>) // </span><span class=identifier>renames </span><span class=identifier>the </span><span class=identifier>instantiation </span><span class=identifier>double_inst </span><span class=special>= </span><span class=identifier>Point</span><span class=special>(</span><span class=string>"double"</span><span class=special>) // </span><span class=identifier>another </span><span class=identifier>way </span><span class=identifier>to </span><span class=keyword>do </span><span class=identifier>the </span><span class=identifier>same </span><span class=identifier>rename</span><span class=special>(</span><span class=identifier>double_inst</span><span class=special>, </span><span class=string>"DPoint"</span><span class=special>) </span></pre></code> <p> Note that you can rename, exclude, set policies, etc, in the <tt>Template</tt> object like you would do with a <tt>Function</tt> or a <tt>Class</tt>. This changes affect all <b>future</b> instantiations:</p> <code><pre> <span class=identifier>Point </span><span class=special>= </span><span class=identifier>Template</span><span class=special>(</span><span class=string>"Point"</span><span class=special>, </span><span class=string>"point.h"</span><span class=special>) </span><span class=identifier>Point</span><span class=special>(</span><span class=string>"float"</span><span class=special>, </span><span class=string>"FPoint"</span><span class=special>) // </span><span class=identifier>will </span><span class=identifier>have </span><span class=identifier>x </span><span class=keyword>and </span><span class=identifier>y </span><span class=identifier>as </span><span class=identifier>data </span><span class=identifier>members </span><span class=identifier>rename</span><span class=special>(</span><span class=identifier>Point</span><span class=special>.</span><span class=identifier>x</span><span class=special>, </span><span class=string>"X"</span><span class=special>) </span><span class=identifier>rename</span><span class=special>(</span><span class=identifier>Point</span><span class=special>.</span><span class=identifier>y</span><span class=special>, </span><span class=string>"Y"</span><span class=special>) </span><span class=identifier>Point</span><span class=special>(</span><span class=string>"int"</span><span class=special>, </span><span class=string>"IPoint"</span><span class=special>) // </span><span class=identifier>will </span><span class=identifier>have </span><span class=identifier>X </span><span class=keyword>and </span><span class=identifier>Y </span><span class=identifier>as </span><span class=identifier>data </span><span class=identifier>members </span><span class=identifier>Point</span><span class=special>(</span><span class=string>"double"</span><span class=special>, </span><span class=string>"DPoint"</span><span class=special>) // </span><span class=identifier>also </span><span class=identifier>will </span><span class=identifier>have </span><span class=identifier>X </span><span class=keyword>and </span><span class=identifier>Y </span><span class=identifier>as </span><span class=identifier>data </span><span class=identifier>member </span></pre></code> <p> If you want to change a option of a particular instantiation, you can do so:</p> <code><pre> <span class=identifier>Point </span><span class=special>= </span><span class=identifier>Template</span><span class=special>(</span><span class=string>"Point"</span><span class=special>, </span><span class=string>"point.h"</span><span class=special>) </span><span class=identifier>Point</span><span class=special>(</span><span class=string>"int"</span><span class=special>, </span><span class=string>"IPoint"</span><span class=special>) </span><span class=identifier>d_inst </span><span class=special>= </span><span class=identifier>Point</span><span class=special>(</span><span class=string>"double"</span><span class=special>, </span><span class=string>"DPoint"</span><span class=special>) </span><span class=identifier>rename</span><span class=special>(</span><span class=identifier>d_inst</span><span class=special>.</span><span class=identifier>x</span><span class=special>, </span><span class=string>"X"</span><span class=special>) // </span><span class=identifier>only </span><span class=identifier>DPoint </span><span class=identifier>is </span><span class=identifier>affect </span><span class=identifier>by </span><span class=keyword>this </span><span class=identifier>renames</span><span class=special>, </span><span class=identifier>rename</span><span class=special>(</span><span class=identifier>d_inst</span><span class=special>.</span><span class=identifier>y</span><span class=special>, </span><span class=string>"Y"</span><span class=special>) // </span><span class=identifier>IPoint </span><span class=identifier>stays </span><span class=identifier>intact </span></pre></code> <table width="80%" border="0" align="center"> <tr> <td class="note_box"> <img src="theme/note.gif"></img> <b>What if my template accepts more than one type?</b> <br><br> When you want to instantiate a template with more than one type, you can pass either a string with the types separated by whitespace, or a list of strings ("int double" or ["int", "double"] would both work). </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="policies.html"><img src="theme/l_arr.gif" border="0"></a></td> <td width="20"><a href="wrappers.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>