Execute multiple python files using a single main

Question

I have multiple python files, each with different classes and methods in it. I want to execute all those files with a main function I have separately outside all of them.

Answer 1

Do you mean you want to import them?

import one
import two
import three

result = one.func()
instance = two.YourClass()
something = three.func()

Note that there is no "main method" in python (perhaps you've been using JAVA?). When you say python thisfile.py, python executes all of the code in "thisfile.py". One neat little trick that we use is that each "module" has an attribute "name". the script invoked directly (e.g. thisfile.py) gets assigned the name "__main__". That allows you to separate the portion of a module which is meant to be a script, and the portion which is meant to be reused elsewhere. A common use case for this is testing:

#file: thisfile.py
def func():
   return 1,2,3

if __name__ == "__main__":
   if func() != (1,2,3):
      print "Error with func"
   else:
      print "func checks out OK"

Now if I run this as python thisfile.py, it will print func checks out OK, but if I import it in another file, e.g:

#anotherfile.py
import thisfile

and then I run that file via python anotherfile.py, nothing will get printed.