On Fri, Feb 21, 2014 at 2:14 AM, Marko Rauhamaa <ma...@pacujo.net> wrote: > * you won't be finding old Python versions on newer operating system > distributions, > > * even <URL: http://www.python.org/downloads/> isn't all that extensive > and > > * the program may import modules that were written in different Python > dialects.
You can always build your own Python, if it really matters... but more likely, if you care about old versions, you actually care about *one specific old version* which your program uses. That's why Red Hat still supports Python 2.4 and, I think, 2.3. You can't randomly pick up 2.2 or 1.5, but if you want 2.4, you can keep on using that for as long as this RHEL is supported. As to importing modules written for other versions... that can be a major problem. Often the new keywords come with new functionality. Take string exceptions, for instance. Say you import a module that was written for a version that still supported them - if it raises a string, you can't catch it. There is a limit to how far the compatibility can be taken. Also, what happens if two modules (one of which might be your script) written for different versions both import some third module? Should they get different versions, based on what version tags they use themselves? Compatibility can't be changed that easily. You either run on the new version, or run on the old. Not both. ChrisA -- https://mail.python.org/mailman/listinfo/python-list