[Python-Dev] Python launcher command line usage (Was: 3.2.1 encoding surprise) (original) (raw)

Paul Moore p.f.moore at gmail.com
Tue Jul 19 17:00:57 CEST 2011

On 19 July 2011 02:41, Vinay Sajip <vinay_sajip at yahoo.co.uk> wrote:

The use of py from the command line is merely a convenience for developers (as the PEP says) - it's better to rely on shebang lines together with settings in the .ini to get the behaviour you want.

But it's a huge convenience for running multiple Python versions, particularly as no existing Python versions install executables with the version in the name (python3.exe, python3.2.exe, etc).And BAT files aren't a suitable option (I'll rant about the issues with BAT files if you want, but I recommend you don't ask :-))

Being able to say py -3, py -2.7, etc, rather than having to hack PATH, create renamed copies of exes, etc, is arguably more of a benefit to me than shebang support.

This may explain why I'd like to see a command-line means of invoking custom commands. Something like py.exe looking at an initial argument, and if it's of the form "-cmd" for a command in py.ini, then run that command, passing remaining arguments just as for py -3. (Maybe --cmd to match standard long option usage would be better?)

Presumably, if this idea is to go anywhere, it would need adding to the PEP. Mark, do you think it would be useful? It makes it possible to invoke IronPython/Jython in the same manner as CPython. (And, of course, to abuse things so that "py -perl" runs Perl, but no-one would do that :-))

Paul.

More information about the Python-Dev mailing list