Python and Jython

[Mulugeta Maru]

I must say thank you very much. Very helpful explanation and advice.


----- Original Message ----- 
From: "Michael Chermside" <mcherm at mcherm.com>
To: <python-list at python.org>; <mmaru at attcanada.ca>
Sent: Tuesday, June 24, 2003 7:49 AM
Subject: Python and Jython


> Mulugeta Maru writes:
> > My background is Java. I would like to know the difference between
Python
> > and Jython. Are they different languages? Should I learn Python first
and
> > then Jython? The reason I would like to learn the language is to use it
with
> > Java.
>
> Jython and Python are the *same* language. This doesn't mean that they
> are identical in all respects... there are several important differences.
> But that's a lot like using Netscape's javascript versus Microsoft's...
> (back before EMCAscript was standardized) if you stick to the basic things
> they'll work the same way in both, but you can find lots of differences
lurking
> in the corners.
>
> The most important differences are the truly fundamental ones that
motivated
> having two different implementations. CPython (the proper name for the
C-based
> version of Python, although people usually just call it "python") is
written in
> C. This means that it can be EXTENDED in C, and there are lots of useful
> extensions (and some built into the standard distribution) that exist for
> CPython which allow OS-specific features like Microsoft com objects and
unix
> interrupts, or to c libraries (several windowing libraries for instance),
or
> c's speed (Numeric and libraries for doing scientific computations).
Jython has
> none of these.
>
> Meanwhile, Jython runs on the java virtual machine (although that isn't
really
> an advantage on portability, since CPython is more portable than the JVM).
The
> most important feature of Jython is that Jython progams can call Java
objects,
> Java programs can call Jython objects, and the Jython can be compiled into
100%
> pure (compiled) Java code! The level of inter-language integration is
really
> astounding, and makes Jython the perfect choice for scripting Java
programs,
> interactively examining Java code, and so forth. Also, it means that
Jython
> programs can take advantage of Java's huge libraries. They have fewer OS-
> specific features, but lots of useful things like JDBC, etc.
>
> The other difference that I've noticed is that a lot more people work on
> CPython than are working on Jython. As a result, CPython is a couple of
> versions ahead of Jython and keeps adding new features. Hopefully Jython
can
> attract more volunteers and manage to keep up (because some of the new
features
> are pretty nice).
>
> There are, of course, some syntactic differences... the page
> http://www.jython.org/docs/differences.html will list some, but it is very
> dated since CPython has changed a lot in since version 2.0 -- for
instance, it
> says that CPython lacks circular garbage collection, but that has since
been
> added. Nevertheless, it's a useful guide.
>
> Since what you want to do is mostly to use Python with Java, I'd suggest
that
> you start out with Jython. You'll find that you can move to CPython
anytime,
> and that nearly everything you learned in Jython will work perfectly
(except
> that which depended on Java libraries).
>
> -- Michael Chermside
>
>