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git-svn-id: https://swig.svn.sourceforge.net/svnroot/swig/trunk/SWIG@4754 626c5289-ae23-0410-ae9c-e8d60b6d4f22
129 lines
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129 lines
4 KiB
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<title>SWIG and Pike</title>
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<h1>SWIG and Pike<br>
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</h1>
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This chapter describes SWIG support for Pike. As of this writing, the
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SWIG Pike module is still under development and is not considered
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ready for prime time. The Pike module is being developed against the
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Pike 7.4.10 release and may not be compatible with previous versions
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of Pike.<p>
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This chapter covers most SWIG features, but certain low-level details
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are covered in less depth than in earlier chapters. At the very
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least, make sure you read the "<a
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href="file:///home/jlj/src/SWIG/Doc/Manual/SWIG.html">SWIG Basics</a>"
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chapter.<br>
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<h2>Preliminaries</h2>
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<h3>Running SWIG</h3>
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Suppose that you defined a SWIG module such as the following:
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<blockquote>
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<pre>%module example<br><br>%{<br>#include "example.h"<br>%}<br><br>int fact(int n);<br></pre>
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</blockquote>
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To build a C extension module for Pike, run SWIG using the <tt>-pike</tt> option :
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<blockquote>
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<pre>$ <b>swig -pike example.i</b><br></pre>
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</blockquote>
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If you're building a C++ extension, be sure to add the <tt>-c++</tt> option:
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<blockquote>
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<pre>$ <b>swig -c++ -pike example.i</b><br></pre>
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</blockquote>
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This creates a single source file named <tt>example_wrap.c</tt> (or <tt>example_wrap.cxx</tt>, if you
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ran SWIG with the <tt>-c++</tt> option).
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The SWIG-generated source file contains the low-level wrappers that need
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to be compiled and linked with the rest of your C/C++ application to
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create an extension module.<p>
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The name of the wrapper file is derived from the name of the input
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file. For example, if the input file is <tt>example.i</tt>, the name
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of the wrapper file is <tt>example_wrap.c</tt>. To change this, you
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can use the <tt>-o</tt> option:
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<blockquote>
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<pre>$ <b>swig -pike -o pseudonym.c example.i</b><br></pre>
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</blockquote>
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<h3>Getting the right header files</h3>
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In order to compile the C/C++ wrappers, the compiler needs to know the
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path to the Pike header files. These files are usually contained in a
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directory such as
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<p> </p>
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<blockquote>
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<pre>/usr/local/pike/7.4.10/include/pike<br></pre>
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</blockquote>
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There doesn't seem to be any way to get Pike itself to reveal the
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location of these files, so you may need to hunt around for them.
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You're looking for files with the names <tt>global.h</tt>, <tt>program.h</tt>
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and so on.
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<h3>Using your module</h3>
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To use your module, simply use Pike's <tt>import</tt> statement:
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<blockquote><pre>
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$ <b>pike</b>
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Pike v7.4 release 10 running Hilfe v3.5 (Incremental Pike Frontend)
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> <b>import example;</b>
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> <b>fact(4);</b>
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(1) Result: 24
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</pre></blockquote>
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<h2>Basic C/C++ Mapping</h2>
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<h3>Modules</h3>
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All of the code for a given SWIG module is wrapped into a single Pike
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module. Since the name of the shared library that implements your
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module ultimately determines the module's name (as far as Pike is
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concerned), SWIG's <tt>%module</tt> directive doesn't really have any
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significance.
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<h3>Functions</h3>
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Global functions are wrapped as new Pike built-in functions. For
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example,
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<blockquote><pre>
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%module example
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int fact(int n);
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</pre></blockquote>
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creates a new built-in function <tt>example.fact(n)</tt> that works
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exactly as you'd expect it to:
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<blockquote><pre>
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> <b>import example;</b>
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> <b>fact(4);</b>
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(1) Result: 24
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</pre></blockquote>
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<h3>Global variables</h3>
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Global variables are currently wrapped as a pair of of functions, one to get
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the current value of the variable and another to set it. For example, the
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declaration
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<blockquote><pre>
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%module example
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double Foo;
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</pre></blockquote>
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will result in two functions, <tt>Foo_get()</tt> and <tt>Foo_set()</tt>:
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<blockquote><pre>
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> <b>import example;</b>
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> <b>Foo_get();</b>
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(1) Result: 3.000000
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> <b>Foo_set(3.14159);</b>
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(2) Result: 0
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> <b>Foo_get();</b>
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(3) Result: 3.141590
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</pre></blockquote>
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<h3>Constants and enumerated types</h3>
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Enumerated types in C/C++ declarations are wrapped as Pike constants,
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not as Pike enums.
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