Python - How to call the main fuction of a module in another module?

Question

I am trying to write a python module that calls the main function of another module in its main function.

The module I am writing is called Trial.py and the module that contains the function to be called is called print_all.py .

print_all.py is a module is a library called mrtparse. The library can be found here.

Note that when I run print_all.py in the Linux shell it requires a file (.gz) as argument as follows

$ python print_all.py updates.gz

Trial.py looks something like this:

from mrtparse import *
import gzip
import print_all   
import os
from urllib2 import urlopen, URLError, HTTPError

def fn1():
    Bla Bla

def fn2():
    Bla Bla

def main():
    mrtparse.print_all.main(updates.gz)  //I want to do something like this

if __name__ == '__main__':
    main()

All the modules and the files to be passed as arguments are in the same directory. It seems like an easy to do thing but I am having such a hard time with it.

Answer 1

I suppose, you should use:

# ...

import print_all

# ...

def main():
    print_all.main("updates.gz") 

Honestly, print_all — is not a module and you cannot import it from any place. Notice, that there is no __init__.py in examples-folder. Otherwise, you will be able to use mrtparse.examples.print_all. But now mrtparse does not see anything in examples.

So, you can put print_all-script near your script and use it like I show above.

After that

Main function in print_all have no arguments. It gets data from command line arguments.

I think, you have two ways:

• Wrong — patch sys.argv;
• Right — rewrite main from print_all.

Patch sys.argv (bad way)

import sys
sys.argv = sys.argv = [sys.argv[0], 'updates.gz']

# ...

import print_all

# ...

def main():
    print_all.main() 

# ...

Rewrite main()

Post this function into print_all and use it instead of main.

def do_work(filename):

    d = Reader(filename)

    # if you want to use 'asdot+' or 'asdot' for AS numbers,
    # comment out either line below.
    # default is 'asplain'.
    #
    # as_repr(AS_REPR['asdot+'])
    # as_repr(AS_REPR['asdot'])
    for m in d:
        m = m.mrt
        print('---------------------------------------------------')
        if m.err == MRT_ERR_C['MRT Header Error']:
            prerror(m)
            continue
        print_mrt(m)

        if m.err == MRT_ERR_C['MRT Data Error']:
            prerror(m)
            continue
        if m.type == MRT_T['TABLE_DUMP']:
            print_td(m)
        elif m.type == MRT_T['TABLE_DUMP_V2']:
            print_td_v2(m)
        elif ( m.type == MRT_T['BGP4MP']
            or m.type == MRT_T['BGP4MP_ET']):
            print_bgp4mp(m)

Right way

Place do_work in your own module or anywhere else in your code. After that, for example, yout file will be look like this:

import sys
from optparse import OptionParser
from datetime import *
from mrtparse import *
from print_all import *
import gzip
import print_all   
import os
from urllib2 import urlopen, URLError, HTTPError


def fn1():
    Bla Bla

def fn2():
    Bla Bla

def do_work(filename):

    d = Reader(filename)

    # if you want to use 'asdot+' or 'asdot' for AS numbers,
    # comment out either line below.
    # default is 'asplain'.
    #
    # as_repr(AS_REPR['asdot+'])
    # as_repr(AS_REPR['asdot'])
    for m in d:
        m = m.mrt
        print('---------------------------------------------------')
        if m.err == MRT_ERR_C['MRT Header Error']:
            prerror(m)
            continue
        print_mrt(m)

        if m.err == MRT_ERR_C['MRT Data Error']:
            prerror(m)
            continue
        if m.type == MRT_T['TABLE_DUMP']:
            print_td(m)
        elif m.type == MRT_T['TABLE_DUMP_V2']:
            print_td_v2(m)
        elif ( m.type == MRT_T['BGP4MP']
            or m.type == MRT_T['BGP4MP_ET']):
            print_bgp4mp(m)


def main():
    do_work('updates.gz') 

if __name__ == '__main__':
    main()