Would it make sense to define a Jython property for the division behavior? Then I could change the syntax to -Ddivision=old, -Ddivision=warn, -Ddivision=new. That's a bit long, but acceptable.
This would be similar to compilers which use -Dsym[=value]. Apache has a similar -Dsym[=value] option.
Note that a general -Dkey=value option would be quite nice. They could all end in sys.startoptions or somesuch. After the -D switches are processed, the startup code can look in the dictionary for "division" to determine what to do.
sys.startoptions would be a generalized way to pass parameters into subsystems which otherwise have no control of the command line. (Apache 2.0 uses this to pass params to the modules which handle request processing) By using sys.startoptions, it would also be portable to systems which don't usually use a command line (Windows, Mac, GUIs, etc); they could potentially get those options from the registry or whatever.
Yes, would be nice - but I have no time for that if I want to make a release this week (or later). I think I'll go for something stupid and simple now, like just using -q to turn on division warnings, and nothing else (the -Dnew option is not very useful I think). --Guido van Rossum (home page: http://www.python.org/~guido/)