Clarifications on a python script file

Question

Just need some clarification on how to design a python script file test.py.

1. When defining functions, do they have to go on the top of the file right after the imports?

2. should I be doing that main check in my file?

3. I want to run this file on my server as a cron job. If the file gets too big (I have my sqlalchemy definitions in it also), how can I break the file into multiple files? I want this easy to deploy by just dropping the files into a folder in my server.

Answer 1

Most scripts look something like the following:

import module1
import module2

CONSTANT=...

def foo():
   ...

def bar():
   ....

class Baz():
   ....

def run(verbose=False):
    ....

if __name__=='__main__':
    import optparse
    def parse_options():
        usage = 'usage: %prog [options]'
        parser = optparse.OptionParser(usage=usage)
        parser.add_option('-v', '--verbose', dest='verbose',
                          action='store_true', 
                          default=False,
                          help="verbose")
        return parser.parse_args()
    def cli():
        opt,args=parse_options()        
        run(verbose=opt.verbose)
    cli()

So the body of your script is mainly composed of function/class definitions. There (usually) is very little code that isn't inside a function/class definition.

I would try to group the functions in whatever way facilitates organization and readability. If you believe a function can be reused in places other than that particular script, then place it in a module, and import that module into this script.

Define PYTHONPATH and PATH in your crontab. Then you should have no problem running your script from cron.