[Python-Dev] Handling of sys.args (Re: User's complaints) (original) (raw)

Guido van Rossum guido at python.org
Thu Jul 13 21:25:50 CEST 2006

On 7/13/06, Ka-Ping Yee <python-dev at zesty.ca> wrote:

On Thu, 13 Jul 2006, Greg Ewing wrote: > Would it help if sys were pre-imported into the builtins? > Or do you think that args shouldn't live in sys at all?

I feel like the command-line arguments don't really belong in sys, and i'd rather not have 'sys' pre-imported into the builtins. I think of 'sys' as the place for sensitive interpreter internals and the builtins as the place for harmless functions. They're at opposite ends of the scale -- 'sys' is the most privileged; builtins are the least privileged. From a security point of view, 'import' is the main way to get dangerous new functionality. I realize 'open' breaks this concept, but it's nice to be able to say, to a rough approximation, that preventing 'import' gives you an interpreter that can do computations but isn't a security risk. These are just my feelings -- i'm not sure how consistent this is with the original intent of 'sys'. I think it would be a quite useful distinction to have, though.

sys is a grab-bag. Note that it also has a good deal of harmless read-only data: maxint, version, platform and many more. But it seems to specialize in things that you may modify to change global behavior: path, modules, stdout, ps1, displayhook and others. I'nm afraid if we were to split it by functionality we'd have to split it 5-way or so...

> And while we're on the subject, anyone think it would > be a good idea to drop the silly feature of having > the program name as args[0]? You almost never want > to treat it the same way as the rest of the args, > so the first thing you always do is args[1:].

Starting the args array with the first argument (and putting the program name somewhere else) seems Pythonic to me.

As long as it's called args, not argv, I agree.

-- --Guido van Rossum (home page: http://www.python.org/~guido/)

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