mirror of https://github.com/swig/swig
114 lines
2.3 KiB
HTML
114 lines
2.3 KiB
HTML
<html>
|
|
<head>
|
|
<title>SWIG:Examples:go:template</title>
|
|
</head>
|
|
|
|
<body bgcolor="#ffffff">
|
|
|
|
|
|
<tt>SWIG/Examples/go/template/</tt>
|
|
<hr>
|
|
|
|
<H2>C++ template support</H2>
|
|
|
|
<p>
|
|
This example illustrates how C++ templates can be used from Go using
|
|
SWIG.
|
|
|
|
<h2>The C++ Code</h2>
|
|
|
|
Let's take a templated function and a templated class as follows:
|
|
|
|
<blockquote>
|
|
<pre>
|
|
/* File : example.h */
|
|
|
|
// Some template definitions
|
|
|
|
template<class T> T max(T a, T b) { return a>b ? a : b; }
|
|
|
|
template<class T> class vector {
|
|
T *v;
|
|
int sz;
|
|
public:
|
|
vector(int _sz) {
|
|
v = new T[_sz];
|
|
sz = _sz;
|
|
}
|
|
T &get(int index) {
|
|
return v[index];
|
|
}
|
|
void set(int index, T &val) {
|
|
v[index] = val;
|
|
}
|
|
#ifdef SWIG
|
|
%extend {
|
|
T getitem(int index) {
|
|
return self->get(index);
|
|
}
|
|
void setitem(int index, T val) {
|
|
self->set(index,val);
|
|
}
|
|
}
|
|
#endif
|
|
};
|
|
</pre>
|
|
</blockquote>
|
|
The %extend is used for a neater interface from Go as the
|
|
functions <tt>get</tt> and <tt>set</tt> use C++ references to
|
|
primitive types. These are tricky to use from Go as they end up as
|
|
pointers, which only work when the C++ and Go types correspond
|
|
precisely.
|
|
|
|
<h2>The SWIG interface</h2>
|
|
|
|
A simple SWIG interface for this can be built by simply grabbing the
|
|
header file like this:
|
|
|
|
<blockquote>
|
|
<pre>
|
|
/* File : example.i */
|
|
%module example
|
|
|
|
%{
|
|
#include "example.h"
|
|
%}
|
|
|
|
/* Let's just grab the original header file here */
|
|
%include "example.h"
|
|
|
|
/* Now instantiate some specific template declarations */
|
|
|
|
%template(maxint) max<int>;
|
|
%template(maxdouble) max<double>;
|
|
%template(vecint) vector<int>;
|
|
%template(vecdouble) vector<double>;
|
|
</pre>
|
|
</blockquote>
|
|
|
|
Note that SWIG parses the templated function <tt>max</tt> and
|
|
templated class <tt>vector</tt> and so knows about them. However to
|
|
generate code for use from Go, SWIG has to be told which class/type to
|
|
use as the template parameter. The SWIG directive %template is used
|
|
for this.
|
|
|
|
<h2>A sample Go program</h2>
|
|
|
|
Click <a href="runme.go">here</a> to see a Go program that calls the
|
|
C++ functions from Go.
|
|
|
|
<h2>Notes</h2> Use templated classes just like you would any other
|
|
SWIG generated Go class. Use the classnames specified by the %template
|
|
directive.
|
|
|
|
<blockquote>
|
|
<pre>
|
|
vecdouble dv = new vecdouble(1000);
|
|
dv.setitem(i, 12.34));
|
|
</pre>
|
|
</blockquote>
|
|
|
|
<hr>
|
|
</body>
|
|
</html>
|