command-line args

[Michael]

What's the perfered method of passing command-line args throughout a
Python program given that globals don't seem to really exist? I thought
of writing them out to a python file and then importing them when
needed.. but that seems like it'd only work for a single process.. not
in instances where more than one user is running the program. There
isn't anything like a virtual file space that could be used for this?
Anyway to set a global variable?

[Peter Hansen]

Re: command-line args

Michael wrote:
[color=blue]
> What's the perfered method of passing command-line args throughout a
> Python program given that globals don't seem to really exist? I thought
> of writing them out to a python file and then importing them when
> needed.. but that seems like it'd only work for a single process.. not
> in instances where more than one user is running the program. There
> isn't anything like a virtual file space that could be used for this?
> Anyway to set a global variable?[/color]

Create an empty module called "globals" and import that wherever
needed. Populate it with settings from the command-line parsing
stage. Get fancier and put defaults in there to begin with, and
override them only if specified in the command-line parsing
area. Flavour as needed...

(That's just one option, but in many ways the simplest. Some of
us also use a simple "bag" type of object which we pass around
as required, but that's more awkward with really large applications.)

-Peter

[Michael]

Re: command-line args

[color=blue]
> Create an empty module called "globals" and import that wherever
> needed. Populate it with settings from the command-line parsing
> stage. Get fancier and put defaults in there to begin with, and
> override them only if specified in the command-line parsing
> area. Flavour as needed...[/color]

What do you do about multiple processes (of the same program) running at
once? Save to /tmp/<pid>/globals.py or something like that?
[color=blue]
> (That's just one option, but in many ways the simplest. Some of
> us also use a simple "bag" type of object which we pass around
> as required, but that's more awkward with really large applications.)[/color]

I've done that before and yeh it is really a hassle with anything very
large.

[Tim Daneliuk]

Re: command-line args

Michael wrote:
[color=blue]
> What's the perfered method of passing command-line args throughout a
> Python program given that globals don't seem to really exist? I thought
> of writing them out to a python file and then importing them when
> needed.. but that seems like it'd only work for a single process.. not
> in instances where more than one user is running the program. There
> isn't anything like a virtual file space that could be used for this?
> Anyway to set a global variable?
>[/color]

If I may be so immodest, I have just released this as another way
to set program options:

http://www.tundraware.com/Software/tconfpy/

Keep your options in a text file with each option in the form:

option = value

Call tconfpy.ParseCo nfig("myconfigf ile") and you'll get back
(among other things) a populated symbol table with each option as
one of the keys...

--
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Tim Daneliuk tundra@tundrawa re.com
PGP Key: http://www.tundraware.com/PGP/