Introduction to Jython

1
Introduction to Jython

• Deepak Ram
• dram_at_india.hp.com

2
Scope

• Not a tutorial
• Gives high level picture
• Not exhaustive
• May prompt the audience to give it a try if not
  already done it.

3
Topics covered

• What is Jython ?
• Features
• Code Examples
• Pros and Cons
• Where it can be used?
• Conclusion

4
What is Jython ?

• 100 pure Java Implementation of Python.
• Dynamic compilation to Java byte codes
• Seamless and smooth integration with java

5
Features

• Interactive interpreter
• gtgtgt from java.util import Random
• gtgtgt r Random()
• gtgtgt r.nextInt()
• -790940041
• Dynamic Variable Creation
• Good High Level Built-In Data Structure
• listOfString One,Two,Three
• print listOfString0

6
Features (Contd.)

• Dynamic Object Oriented Typing
• Complete access to all java libraries
• Embedded Scripting
• Extend Java classes in Jython script
• Optional static compilation
• - allows creation of applets, servlets

7
Features (Contd.)

• Bean Property Introspection
• button.preferredSize (300, 50)
• First class functions
• Event Listener Introspection
• def exit(event)
• java.lang.System.exit(0)
• button awt.Button("Close Me!",
  actionPerformedexit)

8
Examples (List Manipulation)

• Jythongt a 1,2,5,hello Mixed List
• Javagt ArrayList a new ArrayList()
• a.add(new Integer(1))
• a.add(new Integer(2))
• a.add(new Integer(5))
• a.add(hello)

9
Examples (File Handling)

• Jython gt fopen(foo,r) line f.readLine()
• Javagt try
• File file new File(foo)
  f.setReadOnly()
• BufferedInputSteam f null
• f new BufferedInputStream(new
  FileInputSteam(file))
• String data f.readLine()
• catch (IOException e)

10
Examples (GUI)

• Jythongtfrom javax.swing import
• win Jframe(My Frame)
• win.contentPane.add(JButton(Jython))
• win.setSize(300,300)
• win.setVisible(1)

11
Pros

• Dynamic typing/High Level Data Structure
• - Fewer Lines of code (2 10 times fewer
  compared to Java)
• - Higher productivity.
• - Fewer bugs.
• - Better maintainability
• Can make use of existing repository of java and
  Python code.

12
Pros (Contd.)

• Platform independent
• Interactive Experimentation
• Simple and easy to learn syntax
• Java skill not necessary for writing client
  programs for Java code.
• No compilation necessary

13
Cons

• C based extensions in Python not available
• Lower performance compared to compiled Language.
• No extensive documentation
• Lack of awareness among Java Community

14
Where it can be used ?

• Interactive Experimentation
• Rapid Application Development
• Prototyping.
• Training Programmers on use of java libraries.
• Client Programs and Test Drivers.
• Automated Testing
• - PyUnit/JUnit

15
Resources

• http//www.jython.org
• http//www.python.org
• http//gnosis.cx/publish/programming/charming_pyth
  on_10.txt
• Jython Essentials (Samuele Pedroni and Noel
  Rappin, O'Reilly, March 2002)

16
Questions ?