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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="callpolicies.html">prev</a>][<a href="index.html">top</a>][<a href="errors.html">next</a>]<br><h4>Various Goodies<br></h4>This section of the documentation covers a couple of additionalimportant features.<br><br><h4><a name="packages"></a>Package support</h4>It is possible to define a package name and version for the extension.Use the <code>pkg_provide</code> member function when defining aloadable module:<br><br><div style="margin-left: 40px;"><code>CPPTCL_MODULE(Mymodule, i)</code><br><code>{<br> i.pkg_provide("MyPackage", "3.4");<br> // ...<br></code><code></code><code>}</code><br><code></code></div><br>After loading this module inside the Tcl interpreter, the followingcommand shows that the package is indeed provided:<br><br><div style="margin-left: 40px;"><code>% package provide MyPackage</code><br><code>3.4</code><br><code>%</code><br><code></code></div><br><h4><a name="streameval"></a>Stream evaluation</h4>It is possible to evaluate the contents of the input stream. One of thepossible uses is the evaluation of the whole file:<br><br><div style="margin-left: 40px;"><code>ifstream f("somescript.tcl");</code><br><code>i.eval(f);</code><br><code></code></div><br>Any object compatible with <code>std::istream</code> is accepted.<br><h4><a name="namespaces"></a>Tcl Namespaces</h4>Tcl supports namespaces. It is possible to define classes and functionswithin their own namespace by just prefixing the name with thenamespacename:<br><br><div style="margin-left: 40px;"><code>i.def("NS::fun", fun);</code><br></div><br>The above example defines a new function <code>fun</code>, which willbe visible in the <code>NS</code> namespace.<br>The problem is that the Tcl namespace needs to be created before anyname is added to it. This can be done by simple script evaluation.<br>Example:<br><br><div style="margin-left: 40px;"><code>CPPTCL_MODULE(Mymodule, i)</code><br><code>{</code><br><code> i.eval("namespace eval NS {}");</code><br><code> i.def("NS::fun", fun);</code><br><code>}</code><br><code></code></div><br><h4><a name="safe"></a>Safe Tcl Interpreters</h4>Each Tcl interpreter can be turned into a <span style="font-style: italic;">safe</span> interpreter, where dangerouscommands (which are commands related to files, sockets, processcontrol, etc.) cannot be called.<br>This feature may be very useful when user-provided scripts are to beevaluated in the embedded Tcl interpreter. <br>In order to make a safe interpreter, do this:<br><br><div style="margin-left: 40px;"><code>i.make_safe();</code><br></div><br>Once the interpreter is made safe, it cannot be put back to its normalform.<br><br><h4><a name="aliasing"></a>Aliasing</h4>Aliasing is a powerful feature of Tcl. It allows to define <span style="font-style: italic;">links</span> between two interpreters, sothat when one command is invoked in one interpreter, it is justforwarded and executed within the second interpreter. This means thatthe given command will have access to the other interpreter's state(its commands, variables, etc.).<br>This feature is useful when a "firewall" interpreter is created thatprovides access to only selected set of commands defined in anotherinterpreter.<br>In order to make an alias from interpreter <code>i1</code> tointerpreter <code>i2</code>, do this:<br><br><div style="margin-left: 40px;"><code>i1.create_alias("fun", i2,"otherFun");</code><br></div><br>The above instruction creates an alias in the interpreter <code>i1</code>,so that whenever the fun command is invoked in it, it will forward thecall to the second interpreter, to the <code>otherFun</code> command.<br><br><br>[<a href="callpolicies.html">prev</a>][<a href="index.html">top</a>][<a href="errors.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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