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