command-line args

[Peter Hansen]

(Michael, I'm keeping this on the mailing list, if you don't
mind.  I prefer not answering offline questions, unless the
customer is a paying one. ;-)

Michael [mailto:mogmios at mlug.missouri.edu] wrote:
> Peter Hansen wrote:
> > Michael wrote:
> > >What do you do about multiple processes (of the same program) 
> > >running at once?  Save to /tmp/<pid>/globals.py or something like 
> > >that?
> >
> >Why would you save anything?  If you're just parsing command-line 
> >arguments, the settings are not persistent, are they?  Just kept in 
> >memory for the duration of the current program.  If you have multiple 
> >processes, each gets its own command line arguments and thus its own 
> >in-memory values from globals.py.
> >
> In what way can you create a module and import it from other 
> modules without saving it as a file?
> [snip]
> No interest in persisitance. What I'm doing right now creates 
> the globals_<pid>.py file when command-line options are 
> parsed and deletes
> globals_<pid>.py* when the program stops.

What I mean is this.

You create globals.py ahead of time, the usual way with a text
editor.  It can contain defaults if you wish, or be empty. E.g.:

(globals.py)
logging = False
userName = None
timeout = 5.0

Then you simply import this where you are doing the command-line
argument parsing:

import globals, getopt
opts, args = getopt.getopt(sys.argv[1:], 'at:fse:')  # or whatever
for opt, val in opts:
    if opt = '-t':
        globals.timeout = float(val)
    # etc etc


Then, elsewhere where you need to use the values, just do another
import.

(some code that needs to know the timeout)

import globals, time
time.sleep(globals.timeout)
# or whatever


There is no reason to create the .py file on the fly...

(This works because after the first import of a module inside an
application, subsequent imports do *not* re-read the .py file,
but simply get a reference to the already-imported module object
from the sys.modules dictionary.)

-Peter