BSFPerl

BSFPerl Tutorial

This is a very high-level overview of the functionality that BSFPerl provides. The current implementation details are a bit counter-intuitive and are not documented particularly well at the moment.

BSFPerl overloads Perl's import function so that you can also import Java classes into your script. Because '.' is not a valid identifier in Perl, you need to use Perl's usual scoping operator ('::') to separate the components of the package. For example, to refer to java.util.Random you would use java::util::Random.

When import is invoked on a Java class, it will create a Perl package named with the class part of the import (e.g., Random). Any subsequent method calls that are attempted on this package will be forwarded on to Java, which will search for a static method of the appropriate signature.

BSFPerl treats a method call to new differently; instead of looking for a static method with that name, it looks for a constructor that takes the appropriate arguments. If found, the constructor is invoked and a proxy to the constructed object is returned.

Method calls on proxy objects will also be forwarded to Java. Various data type conversions will be performed both on the input arguments as well as the return value.

Here's an example that covers all of this functionality:

    import javax::swing::JFrame;
    import javax::swing::JButton;
    import java::awt::BorderLayout;
    
    my $f = new JFrame("test");
    my $b = new JButton("Go");
    
    $f->getContentPane->setLayout(new BorderLayout());
    $f->add($b);
    
    $f->pack;
    $f->setVisible(1);

This example will create a JFrame and display it to the user. Unfortunately, there is currently no way to implement Java interfaces from BSFPerl. This means that you cannot register an ActionListener from Perl. In future versions of BSFPerl, this will be changed so that an anonymous subroutine can be passed in place of the interface or bound to specific methods in the interface.