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| <h1 align="center"><a href="../index.html">Boost.Python</a></h1> |
| |
| <h2 align="center">Header <boost/python/exec.hpp></h2> |
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| |
| <h2>Contents</h2> |
| |
| <dl class="page-index"> |
| <dt><a href="#introduction">Introduction</a></dt> |
| |
| <dt><a href="#functions">Functions</a></dt> |
| |
| <dd> |
| <dl class="page-index"> |
| <dt><a href="#eval-spec"><code>eval</code></a></dt> |
| <dt><a href="#exec-spec"><code>exec</code></a></dt> |
| <dt><a href="#exec_file-spec"><code>exec_file</code></a></dt> |
| </dl> |
| </dd> |
| <dt><a href="#examples">Examples</a></dt> |
| </dl> |
| <hr> |
| |
| <h2><a name="introduction"></a>Introduction</h2> |
| |
| <p>Exposes a mechanism for embedding the python interpreter into C++ code.</p> |
| |
| <h2><a name="functions"></a>Functions</h2> |
| |
| <h3><a name="eval-spec"></a><code>eval</code></h3> |
| <pre> |
| object eval(str expression, |
| object globals = object(), |
| object locals = object()); |
| </pre> |
| <dl class="function-semantics"> |
| <dt><b>Effects:</b> |
| Evaluate Python expression from <code>expression</code> in the context |
| specified by the dictionaries <code>globals</code> and <code>locals</code>. |
| </dt> |
| <dt><b>Returns:</b> |
| An instance of <a href="object.html#object-spec">object</a> |
| which holds the value of the expression. |
| </dt> |
| </dl> |
| |
| <h3><a name="exec-spec"></a><code>exec</code></h3> |
| <pre> |
| object exec(str code, |
| object globals = object(), |
| object locals = object()); |
| </pre> |
| <dl class="function-semantics"> |
| <dt><b>Effects:</b> |
| Execute Python source code from <code>code</code> in the context |
| specified by the dictionaries <code>globals</code> and <code>locals</code>. |
| </dt> |
| <dt><b>Returns:</b> |
| An instance of <a href="object.html#object-spec">object</a> |
| which holds the result of executing the code. |
| </dt> |
| </dl> |
| |
| <h3><a name="exec_file-spec"></a><code>exec_file</code></h3> |
| <pre> |
| object exec_file(str filename, |
| object globals = object(), |
| object locals = object()); |
| </pre> |
| <dl class="function-semantics"> |
| <dt><b>Effects:</b> |
| Execute Python source code from the file named by <code>filename</code> |
| in the context specified by the dictionaries <code>globals</code> and |
| <code>locals</code>. |
| </dt> |
| <dt><b>Returns:</b> |
| An instance of <a href="object.html#object-spec">object</a> |
| which holds the result of executing the code. |
| </dt> |
| </dl> |
| |
| <h2><a name="examples"></a>Examples</h2> |
| |
| <para>The following example demonstrates the use of <function>import</function> |
| and <function>exec</function> to define a function in python, and later call |
| it from within C++.</para> |
| |
| <pre> |
| #include <iostream> |
| #include <string> |
| |
| using namespace boost::python; |
| |
| void greet() |
| { |
| // Retrieve the main module. |
| object main = import("__main__"); |
| |
| // Retrieve the main module's namespace |
| object global(main.attr("__dict__")); |
| |
| // Define greet function in Python. |
| object result = exec( |
| "def greet(): \n" |
| " return 'Hello from Python!' \n", |
| global, global); |
| |
| // Create a reference to it. |
| object greet = global["greet"]; |
| |
| // Call it. |
| std::string message = extract<std::string>(greet()); |
| std::cout << message << std::endl; |
| } |
| </pre> |
| |
| <para>Instead of embedding the python script into a string, |
| we could also store it in an a file...</para> |
| |
| <pre> |
| def greet(): |
| return 'Hello from Python!' |
| </pre> |
| <para>... and execute that instead.</para> |
| <pre> |
| // ... |
| // Load the greet function from a file. |
| object result = exec_file(script, global, global); |
| // ... |
| } |
| </pre> |
| <p>Revised 01 November, 2005</p> |
| |
| <p><i>© Copyright Stefan Seefeld 2005.</i></p> |
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