calling an outside function in python

I am trying to return (execute) a function from another file in an if statement. I have read that the return statement will not work, I was hoping someone would know what statement would allow me to call an outside function.

The function creates a sandbox but if one exists I want to pass the if statement.

This is a small snippet of c开发者_StackOverflow社区ode I used.

import mks_function  
from mksfunction import mks_create_sandbox  
import sys, os, time  
import os.path  

if not os.path.exists('home/build/test/new_sandbox/project.pj'):
 return mks_create_sandbox()  
else:  
 print pass  

---

Say your function bar is in a file called foo.py on your Python path.

If foo.py contains this:

def bar():
  return True

Then you can do this:

from foo import bar

if bar():
  print "bar() is True!"

---

let's see what docs say:

return may only occur syntactically nested in a function definition, not within a nested class definition.

what you're trying to do, I guess is:

from mksfunction import mks_create_sandbox  
import os.path

if not os.path.exists('home/build/test/new_sandbox/project.pj'):
    mks_create_sandbox()

---

I have a big touch on this recently as I was working on my final project in python. I would be engaged to look at your outside function file too.

If you are calling a module (well actually, any function outside the same file can be treated as a module, I hate to specify things too precise), you need to make sure something. Here is an example of a module, let's called it my_module.py

# Example python module

import sys
# Any other imports... imports should always be first

# Some classes, functions, whatever...
# This is your meat and potatos

# Now we'll define a main function
def main():
    # This is the code that runs when you are running this module alone
    print sys.platform

# This checks whether this file is being run as the main script
#  or if its being run from another script
if __name__ == '__main__':
    main()
# Another script running this script (ie, in an import) would use it's own
#  filename as the value of __name__

Now I want to call this entire function in another file, called work.py

import my_module

x = my_module
x.main()

---

You probably need to import the module which contains the function, no?

Of course, a little more precision as to what you are trying to achieve would help.

---

What exactly do you mean by "the return statement will not work"?

You can import the function from the other file and call it like a local function.

---

It depends what you mean. If you want to create a static method then you would do something like

class fubar(object):

    @classmethod
    def foo():
      return bar

fubar.foo() # returns bar

If you want to run an external process then you would use subprocess library and do

import subprocess
subprocess.popen("cmd echo 'test'",shell=true)

really depends what you want to do

---

Do you mean import? Say, your external function lives in mymodule.py in the same directory, you have to import it first:

import mymodule
# or
from mymodule import myfunction

Then it is straight forward to use the function:

if mymodule.myfunction() == "abc":
    # do something

or with the second import:

if myfunction() == "abc":
    # do something

See this tutorial.

---

file1.py (comment out 2 of the versions)

#version 1
from file2 import outsidefunction
print (outsidefunction(3))

#version 2
import file2
print (file2.outsidefunction(3))

#version 3
from file2 import *
print (outsidefunction(3))

file2.py

def outsidefunction(num):
    return num * 2

Command-Line: python file1.py