34c97ffdbd
Fix numerous inaccuracies in index.html (where it exists) and eliminate unnecessary differences between the example code being wrapped.
157 lines
2.8 KiB
HTML
157 lines
2.8 KiB
HTML
<html>
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<head>
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<title>SWIG:Examples:perl5:class</title>
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</head>
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<body bgcolor="#ffffff">
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<tt>SWIG/Examples/perl5/class/</tt>
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<hr>
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<H2>Wrapping a simple C++ class</H2>
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<p>
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This example illustrates the most primitive form of C++ class wrapping performed
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by SWIG. In this case, C++ classes are simply transformed into a collection of
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C-style functions that provide access to class members.
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<h2>The C++ Code</h2>
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Suppose you have some C++ classes described by the following (and admittedly lame)
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header file:
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<blockquote>
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<pre>
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/* File : example.h */
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class Shape {
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public:
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Shape() {
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nshapes++;
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}
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virtual ~Shape() {
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nshapes--;
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}
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double x, y;
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void move(double dx, double dy);
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virtual double area() = 0;
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virtual double perimeter() = 0;
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static int nshapes;
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};
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class Circle : public Shape {
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private:
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double radius;
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public:
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Circle(double r) : radius(r) { }
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virtual double area();
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virtual double perimeter();
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};
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class Square : public Shape {
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private:
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double width;
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public:
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Square(double w) : width(w) { }
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virtual double area();
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virtual double perimeter();
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};
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</pre>
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</blockquote>
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<h2>The SWIG interface</h2>
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A simple SWIG interface for this can be built by simply grabbing the header file
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like this:
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<blockquote>
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<pre>
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/* File : example.i */
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%module example
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%{
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#include "example.h"
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%}
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/* Let's just grab the original header file here */
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%include "example.h"
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</pre>
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</blockquote>
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Note: when creating a C++ extension, you must run SWIG with the <tt>-c++</tt> option like this:
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<blockquote>
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<pre>
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% swig -c++ -perl example.i
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</pre>
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</blockquote>
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<h2>A sample Perl script</h2>
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Click <a href="runme.pl">here</a> to see a script that calls the C++ functions from Perl.
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<h2>Key points</h2>
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<ul>
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<li>To create a new object, you call a constructor like this:
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<blockquote>
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<pre>
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$c = new example::Circle(10.0);
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</pre>
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</blockquote>
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<p>
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<li>You can access member data like so:
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<blockquote>
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<pre>
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$c->{x} = 15; # Set member data
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$x = $c->{x}; # Get member data
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</pre>
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</blockquote>
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<p>
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<li>To invoke a member function, you simply do this:
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<blockquote>
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<pre>
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print "The area is ", $c->area();
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</pre>
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</blockquote>
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<p>
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<li>To invoke a destructor, simply do this:
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<blockquote>
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<pre>
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$c->DESTROY(); # Deletes a shape
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</pre>
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</blockquote>
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<p>
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<li>Static member variables are wrapped like so:
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<blockquote>
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<pre>
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$n = $example::Shape::nshapes; # Get a static data member
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$example::Shapes::nshapes = 13; # Set a static data member
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</pre>
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</blockquote>
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</ul>
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<h2>General Comments</h2>
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<ul>
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<li>SWIG <b>does</b> know how to properly perform upcasting of objects in an inheritance
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hierarchy (including multiple inheritance). Therefore it is perfectly safe to pass
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an object of a derived class to any function involving a base class.
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<li>C++ Namespaces - %nspace isn't yet supported for Perl.
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</ul>
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<hr>
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</body>
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</html>
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