Proposal for .py2, py3, etc. extensions. Was: A way to accommodate laguage changes

[Terry Reedy]

> In the interest of proposing a solution everyone can live with, may
I
> suggest adoption of new module name extensions? A module named
"module.py2"

Perhaps .py3 for 3.0, the release that cannot run old code.

> will not be picked up or understood by Python 1.x on any platforms
that I am
> aware of. These would be compiled to either ".pyc", ".py2c", or
".pc2",
> depending on whether one can compile the new semantics into code old
> interpreters can handle, and whether it is now okay to allow more
than 3
> letters in file extensions on all popular platforms and file
systems. But
> hopefully everyone gets the idea.

Windows (at least some versions) limited to 3 chars as far as I know.
However, since compiled files are version-specific implementation
'buffers' (and not part of the language definition) with an internal
version identifier (I'm sure), py3 could still be compiled to .pyc

Terry J. Reedy