1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>SWIG and Pike</title>
<link rel="stylesheet" type="text/css" href="style.css">
</head>
<body bgcolor="#ffffff">
<H1><a name="Pike"></a>35 SWIG and Pike</H1>
<!-- INDEX -->
<div class="sectiontoc">
<ul>
<li><a href="#Pike_nn2">Preliminaries</a>
<ul>
<li><a href="#Pike_nn3">Running SWIG</a>
<li><a href="#Pike_nn4">Getting the right header files</a>
<li><a href="#Pike_nn5">Using your module</a>
</ul>
<li><a href="#Pike_nn6">Basic C/C++ Mapping</a>
<ul>
<li><a href="#Pike_nn7">Modules</a>
<li><a href="#Pike_nn8">Functions</a>
<li><a href="#Pike_nn9">Global variables</a>
<li><a href="#Pike_nn10">Constants and enumerated types</a>
<li><a href="#Pike_nn11">Constructors and Destructors</a>
<li><a href="#Pike_nn12">Static Members</a>
</ul>
</ul>
</div>
<!-- INDEX -->
<p>
This chapter describes SWIG support for Pike. As of this writing, the
SWIG Pike module is still under development and is not considered
ready for prime time. The Pike module is being developed against the
Pike 7.4.10 release and may not be compatible with previous versions
of Pike.
</p>
<p>
This chapter covers most SWIG features, but certain low-level details
are covered in less depth than in earlier chapters. At the very
least, make sure you read the "<a href="SWIG.html#SWIG">SWIG Basics</a>"
chapter.<br>
</p>
<H2><a name="Pike_nn2"></a>35.1 Preliminaries</H2>
<H3><a name="Pike_nn3"></a>35.1.1 Running SWIG</H3>
<p>
Suppose that you defined a SWIG module such as the following:
</p>
<div class="code">
<pre>%module example<br><br>%{<br>#include "example.h"<br>%}<br><br>int fact(int n);<br></pre>
</div>
<p>
To build a C extension module for Pike, run SWIG using the <tt>-pike</tt> option :
</p>
<div class="code">
<pre>$ <b>swig -pike example.i</b><br></pre>
</div>
<p>
If you're building a C++ extension, be sure to add the <tt>-c++</tt> option:
</p>
<div class="code">
<pre>$ <b>swig -c++ -pike example.i</b><br></pre>
</div>
<p>
This creates a single source file named <tt>example_wrap.c</tt> (or <tt>example_wrap.cxx</tt>, if you
ran SWIG with the <tt>-c++</tt> option).
The SWIG-generated source file contains the low-level wrappers that need
to be compiled and linked with the rest of your C/C++ application to
create an extension module.
</p>
<p>
The name of the wrapper file is derived from the name of the input
file. For example, if the input file is <tt>example.i</tt>, the name
of the wrapper file is <tt>example_wrap.c</tt>. To change this, you
can use the <tt>-o</tt> option:
</p>
<div class="code">
<pre>$ <b>swig -pike -o pseudonym.c example.i</b><br></pre>
</div>
<H3><a name="Pike_nn4"></a>35.1.2 Getting the right header files</H3>
<p>
In order to compile the C/C++ wrappers, the compiler needs to know the
path to the Pike header files. These files are usually contained in a
directory such as
</p>
<div class="code">
<pre>/usr/local/pike/7.4.10/include/pike<br></pre>
</div>
<p>
There doesn't seem to be any way to get Pike itself to reveal the
location of these files, so you may need to hunt around for them.
You're looking for files with the names <tt>global.h</tt>, <tt>program.h</tt>
and so on.
</p>
<H3><a name="Pike_nn5"></a>35.1.3 Using your module</H3>
<p>
To use your module, simply use Pike's <tt>import</tt> statement:
</p>
<div class="code"><pre>
$ <b>pike</b>
Pike v7.4 release 10 running Hilfe v3.5 (Incremental Pike Frontend)
> <b>import example;</b>
> <b>fact(4);</b>
(1) Result: 24
</pre></div>
<H2><a name="Pike_nn6"></a>35.2 Basic C/C++ Mapping</H2>
<H3><a name="Pike_nn7"></a>35.2.1 Modules</H3>
<p>
All of the code for a given SWIG module is wrapped into a single Pike
module. Since the name of the shared library that implements your
module ultimately determines the module's name (as far as Pike is
concerned), SWIG's <tt>%module</tt> directive doesn't really have any
significance.
</p>
<H3><a name="Pike_nn8"></a>35.2.2 Functions</H3>
<p>
Global functions are wrapped as new Pike built-in functions. For
example,
</p>
<div class="code"><pre>
%module example
int fact(int n);
</pre></div>
<p>
creates a new built-in function <tt>example.fact(n)</tt> that works
exactly as you'd expect it to:
</p>
<div class="code"><pre>
> <b>import example;</b>
> <b>fact(4);</b>
(1) Result: 24
</pre></div>
<H3><a name="Pike_nn9"></a>35.2.3 Global variables</H3>
<p>
Global variables are currently wrapped as a pair of functions, one to get
the current value of the variable and another to set it. For example, the
declaration
</p>
<div class="code"><pre>
%module example
double Foo;
</pre></div>
<p>
will result in two functions, <tt>Foo_get()</tt> and <tt>Foo_set()</tt>:
</p>
<div class="code"><pre>
> <b>import example;</b>
> <b>Foo_get();</b>
(1) Result: 3.000000
> <b>Foo_set(3.14159);</b>
(2) Result: 0
> <b>Foo_get();</b>
(3) Result: 3.141590
</pre></div>
<H3><a name="Pike_nn10"></a>35.2.4 Constants and enumerated types</H3>
<p>
Enumerated types in C/C++ declarations are wrapped as Pike constants,
not as Pike enums.
</p>
<H3><a name="Pike_nn11"></a>35.2.5 Constructors and Destructors</H3>
<p>
Constructors are wrapped as <tt>create()</tt> methods, and destructors are
wrapped as <tt>destroy()</tt> methods, for Pike classes.
</p>
<H3><a name="Pike_nn12"></a>35.2.6 Static Members</H3>
<p>
Since Pike doesn't support static methods or data for Pike classes, static
member functions in your C++ classes are wrapped as regular functions and
static member variables are wrapped as pairs of functions (one to get the
value of the static member variable, and another to set it). The names of
these functions are prepended with the name of the class.
For example, given this C++ class declaration:
</p>
<div class="code"><pre>
class Shape
{
public:
static void print();
static int nshapes;
};
</pre></div>
<p>
SWIG will generate a <tt>Shape_print()</tt> method that invokes the static
<tt>Shape::print()</tt> member function, as well as a pair of methods,
<tt>Shape_nshapes_get()</tt> and <tt>Shape_nshapes_set()</tt>, to get and set
the value of <tt>Shape::nshapes</tt>.
</p>
</body>
</html>
|
