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