Python: calling function from imported file

Question

How do you call a function from an imported file? for example:

Test:

import test2
def aFunction():
    print "hi there"

Test2:

import test
aFunction()

This give me a name error, saying my function isn't defined. I've also tried:

from test import aFunction

And:

from test import *

I've also tried not importing test2 in test. I'm coming to Python from C++, so I fear I'm missing something blatantly obvious to veteran Python progammers...

Answer 1

You are creating a circular import. test.py imports test2.py which tries to import test.py.

Don't do this. By the time test2 imports test, that module has not completed executing all the code; the function is not yet defined:

• test is compiled and executed, and an empty module object is added to sys.modules.

• The line import test2 is run.

  • test2 is compiled and executed, and an empty module object is added to sys.modules.

  • The line import test is run.

    • test is already present as a module in sys.modules, this object is returned and bound to the name test.

  • A next line tries to run test.aFunction(). No such name exists in test. An exception is raised.

• The lines defining def aFunction() are never executed, because an exception was raised.

Remove the import test2 line, and run test2.py directly, and importing the function will work fine:

import test

test.aFunction()