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164 lines
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164 lines
4.7 KiB
HTML
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<!-- Copyright David Abrahams 2006. Distributed under the Boost -->
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<!-- Software License, Version 1.0. (See accompanying -->
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<!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) -->
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
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<link rel="stylesheet" type="text/css" href="../boost.css">
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<title>Boost.Python - <boost/python/exec.hpp></title>
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</head>
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<body>
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<table border="0" cellpadding="7" cellspacing="0" width="100%" summary=
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"header">
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<tr>
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<td valign="top" width="300">
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<h3><a href="../../../../index.htm"><img height="86" width="277"
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alt="C++ Boost" src="../../../../boost.png" border="0"></a></h3>
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</td>
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<td valign="top">
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<h1 align="center"><a href="../index.html">Boost.Python</a></h1>
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<h2 align="center">Header <boost/python/exec.hpp></h2>
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</td>
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</tr>
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</table>
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<hr>
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<h2>Contents</h2>
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<dl class="page-index">
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<dt><a href="#introduction">Introduction</a></dt>
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<dt><a href="#functions">Functions</a></dt>
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<dd>
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<dl class="page-index">
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<dt><a href="#eval-spec"><code>eval</code></a></dt>
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<dt><a href="#exec-spec"><code>exec</code></a></dt>
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<dt><a href="#exec_file-spec"><code>exec_file</code></a></dt>
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</dl>
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</dd>
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<dt><a href="#examples">Examples</a></dt>
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</dl>
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<hr>
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<h2><a name="introduction"></a>Introduction</h2>
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<p>Exposes a mechanism for embedding the python interpreter into C++ code.</p>
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<h2><a name="functions"></a>Functions</h2>
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<h3><a name="eval-spec"></a><code>eval</code></h3>
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<pre>
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object eval(str expression,
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object globals = object(),
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object locals = object());
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</pre>
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<dl class="function-semantics">
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<dt><b>Effects:</b>
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Evaluate Python expression from <code>expression</code> in the context
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specified by the dictionaries <code>globals</code> and <code>locals</code>.
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</dt>
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<dt><b>Returns:</b>
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An instance of <a href="object.html#object-spec">object</a>
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which holds the value of the expression.
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</dt>
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</dl>
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<h3><a name="exec-spec"></a><code>exec</code></h3>
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<pre>
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object exec(str code,
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object globals = object(),
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object locals = object());
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</pre>
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<dl class="function-semantics">
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<dt><b>Effects:</b>
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Execute Python source code from <code>code</code> in the context
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specified by the dictionaries <code>globals</code> and <code>locals</code>.
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</dt>
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<dt><b>Returns:</b>
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An instance of <a href="object.html#object-spec">object</a>
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which holds the result of executing the code.
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</dt>
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</dl>
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<h3><a name="exec_file-spec"></a><code>exec_file</code></h3>
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<pre>
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object exec_file(str filename,
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object globals = object(),
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object locals = object());
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</pre>
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<dl class="function-semantics">
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<dt><b>Effects:</b>
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Execute Python source code from the file named by <code>filename</code>
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in the context specified by the dictionaries <code>globals</code> and
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<code>locals</code>.
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</dt>
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<dt><b>Returns:</b>
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An instance of <a href="object.html#object-spec">object</a>
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which holds the result of executing the code.
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</dt>
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</dl>
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<h2><a name="examples"></a>Examples</h2>
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<para>The following example demonstrates the use of <function>import</function>
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and <function>exec</function> to define a function in python, and later call
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it from within C++.</para>
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<pre>
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#include <iostream>
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#include <string>
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using namespace boost::python;
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void greet()
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{
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// Retrieve the main module.
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object main = import("__main__");
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// Retrieve the main module's namespace
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object global(main.attr("__dict__"));
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// Define greet function in Python.
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object result = exec(
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"def greet(): \n"
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" return 'Hello from Python!' \n",
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global, global);
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// Create a reference to it.
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object greet = global["greet"];
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// Call it.
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std::string message = extract<std::string>(greet());
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std::cout << message << std::endl;
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}
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</pre>
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<para>Instead of embedding the python script into a string,
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we could also store it in an a file...</para>
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<pre>
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def greet():
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return 'Hello from Python!'
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</pre>
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<para>... and execute that instead.</para>
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<pre>
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// ...
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// Load the greet function from a file.
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object result = exec_file(script, global, global);
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// ...
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}
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</pre>
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<p>Revised 01 November, 2005</p>
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<p><i>© Copyright Stefan Seefeld 2005.</i></p>
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</body>
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</html>
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