WhyJython

Jython, lest you do not know of it, is the most compelling weapon the Java platform has for its survival into the 21st century - SeanMcGrath

Why Jython

There are numerous alternative languages implemented for the Java VM. The following features help to separate Jython from the rest:

• Dynamic compilation to Java bytecodes - leads to highest possible performance without sacrificing interactivity.
• Ability to extend existing Java classes in Jython - allows effective use of abstract classes.
• Optional static compilation - allows creation of applets, servlets, beans, ...
• Bean Properties - make use of Java packages much easier.
• Python Language - combines remarkable power with very clear syntax. It also supports a full object-oriented programming model which makes it a natural fit for Java's OO design.

What Does Jython Do Well?

• Prototyping
• Java investigation

  •     >>> from java.util import Date
        >>> d = Date()
        >>> print d
        Sat Jan 08 16:26:16 CST 2005
        >>> from java.util import Random
        >>> print dir(Random)
        ['__init__', 'nextBoolean', 'nextBytes', 'nextDouble', 'nextFloat',
        'nextGaussian', 'nextInt', 'nextLong', 'seed', 'setSeed']
        >>>

• Making bean properties accessible

  •     >>> print Date().time
        1105500911121

• Glues together libraries already written in Java
• Excellent embedded scripting language
  • Object Domain UML Tool

  • PushToTest

  • Drools

Differences - Python & Jython

Python 2.7

• C
• Multi-platform
• Compiles to .pyc
• Extend with C

• GIL ¹

• Python garbage collection, which mixes ref counting and mark and sweep

Jython 2.7

• Written mostly in Java, does use Java Native Runtime for C access, but works with security manager restrictions
• Java 7 or Java 8
• Compiles to $py.class files
• Extend with Java or C using JFFI; full CFFI, ctypes, and C Extension API support planned for the future
• Truly multi-threaded
• Java garbage collection, including choice of standard Java GCs; but also provides same API as Python 2.7 to observe GC