[Python-talk] using old .pyc files

[Kent Johnson]

David Betz wrote:
>> The virtual machine and bytecode representation used by CPython are  
>> considered implementation details, not part of the language  
>> definition. Jython (compiles to Java VM) and IronPython (compiles  
>> to .NET CLR) are alternative implementations of the language that  
>> do not use the same bytecode representation. PyPy is another  
>> implementation of the language with its own back-end.
>>     
>
> Do CPython, Jython and IronPython all implement the same source level  
> language or are there differences?
>   
Jython implements Python 2.1 pretty faithfully. There are some CPython 
library modules that are missing in Jython and a few other minor 
differences but the language is essentially the same. (An old list of 
differences is here - http://www.jython.org/docs/differences.html. I 
don't think this list has kept up with CPython but it gives a good idea 
of the kind of differences.) The Jython magic comes from its ability to 
integrate with Java, not from implementing a different language. As the 
Jython developers work toward an implementation of Python 2.2 and 2.3, a 
primary goal is to run the CPython test suite without error.

My impression is that the Python test suite is considered the best 
definition of the language. I think there is some effort to eliminate or 
isolate tests which depend on the implementation from tests which are 
considered normative.

I don't know much about IronPython but I think it is a similar story 
there, except it implements Python 2.4.

Kent