How is the versioning of Jython? - jython

Question

How is the versioning of Jython? If I install Jython 2.5 does it mean that I can program in Python 2.5 syntax in spite of Python3.3 or the Jython versioning system is dependent?
By now the last version of Jython available for production is 2.5.3. If the versioning of Jython is based on Python, it looks deluding to be able to program only In Python 2.5 or earlier.

Answer 1

Jython x.y.z means that it's spec compatible with Python x.y, e.g. Jython 2.5.3 is compatible with Python 2.5 versions. (Python 2.5 introduced the "with" statement aka context manage. This has been implemented in Jython 2.5.)
As implementing each new version is a lot of work and the Jython project has not enough resources to keep up with all versions it was decided to not implement all intermediate versions.
The PyPy project aims to avoid this by abstracting and automating the transformation to a concrete runtime system (native, jvm, .net, etc.)
I don't understand the part "in spite of Python 3.3" in your question.

Answer 2

1.3 Is Jython the same language as Python?
Yes. Jython is an implementation of the Python language in Java. We strive to ensure that Jython remains as compatible with CPython as possible. The latest Jython release (2.2) implements the same language as CPython 2.2 and many of the CPython standard library modules.
There are two incompatibilities with modern CPython that often catch newcomers. First, Jython 2.2 does not implement any features added to CPython in version 2.3 or later. This includes language features such as decorators, and library modules such as optparse. A more modern version of Jython is under active development.
Second, Jython programs cannot use CPython extension modules written in C. These modules usually have files with the extension .pyc, .pyd or .dll. If you want to use such a module, you should look for an equivalent written in pure Python or Java.
There are a number of other differences between the two implementations that are unlikely to go away. These range from the trivial - Jython's code objects don't have a co_code attribute because they don't have any Python bytecodes; to the significant - Jython uses Java's true garbage collection rather than Python's reference counting scheme.
http://jython.sourceforge.net/docs/differences.html
Python has never really had much of a language definition beyond it's C-based implementation. The existence of Jython changed that for the first time and will hopefully lead to a much clearer sense of what Python the language is; independent of any specific implementation.
From: http://www.jython.org/archive/22/userfaq.html#id4
To me it seems that you only have access to Python2.5 if you are using Jython 2.5.3.