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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head> <meta content="text/html; charset=ISO-8859-1" http-equiv="content-type"> <title>C++/Tcl</title></head><body><table style="width: 100%; text-align: left;" border="0" cellpadding="2" cellspacing="20"> <tbody> <tr> <td style="vertical-align: top;"><font size="+3"><span style="font-family: helvetica,arial,sans-serif; font-weight: bold; color: rgb(0, 0, 255);">C++/Tcl</span></font><br> <span style="font-family: helvetica,arial,sans-serif; color: rgb(0, 0, 255); font-weight: bold;">AC++ library for interoperability between C++ and Tcl</span> </td> <td style="vertical-align: top; text-align: right;"><br> </td> </tr> </tbody></table><br>[<a href="quickstart.html">prev</a>][<a href="index.html">top</a>][<a href="classes.html">next</a>]<br><h4>Exposing Free Functions<br></h4>You have already seen an example of how to expose a free C++ functionto the Tcl interpreter.<br>No matter whether you write an extension module or embed Tcl in a C++application, the way to expose a free function is alway the same:<br><br><div style="margin-left: 40px;"><code>i.def("tcl_function_name",cpp_function_name);</code><br></div><br>where <code>i</code> is the name of the interpreter object.<br>In the above example, the <code>"tcl_function_name"</code> is a namethat will be visible to the Tcl scripts and the <code>cpp_function_name</code>is a name of (or a pointer to) the function in the C++ code.<br>They do not have to be the same, although this is a usual practice,like in the <a href="quickstart.html">Quick Start</a> examples:<br><br><div style="margin-left: 40px;"><code>i.def("hello", hello);</code><br></div><br>In fact, anything that is a valid command name in Tcl can be used asthe first parameter.<br>For example, let's suppose that we want to expose the following C++function:<br><br><div style="margin-left: 40px;"><code>int sum(int a, int b)<br>{<br> return a + b;<br>}</code><br></div><br>later we can define it in the interpreter like this:<br><br><div style="margin-left: 40px;"><code>i.def("<span style="font-weight: bold;">add</span>", sum);</code><br><code>i.def("<span style="font-weight: bold;">+</span>", sum);</code><br><code></code></div><br>so that we can call the <code>sum</code> function from Tcl like this:<br><br><div style="margin-left: 40px;"><code>add 3 4</code><br></div><br>or:<br><br><div style="margin-left: 40px;"><code>+ 3 4</code><br></div><br>As you see, the same function can be defined in the interpreter morethan once, with different Tcl names.<br>If you try to define some function with the name that is alreadyregistered, the old registration will be overwritten.<br><br>You have also noticed that the exposed functions can have parametersand return values.<br>Functions with up to 9 parameters can be exposed.<br><br>At the moment, parameters and the return value of exposed functions canhave the following types:<br><ul> <li>std::string, char const *<br> </li> <li>int,</li> <li>long,</li> <li>bool,</li> <li>double,</li> <li>pointer to arbitrary type</li> <li><a href="objects.html">object</a><br> </li></ul>In addition, the parameter of the function can be of type <code>Tconst &</code>, where T is any of the above.<br>This means that only <span style="font-style: italic;">input</span>parameters are supported (this may change in future versions of thelibray).<br><br><br>[<a href="quickstart.html">prev</a>][<a href="index.html">top</a>][<a href="classes.html">next</a>]<br><br><hr style="width: 100%; height: 2px;">Copyright © 2004-2006,MaciejSobczak<br><br></body></html>⌨️ 快捷键说明
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