split python source code into multiple files?

Question

I have a code that I wish to split apart into multiple files. In matlab one can simply call a .m file, and as long as it is not defined as anything in particular it will just run as if it were part of the called code. Example (edited):
test.m (matlab)

function [] = test()
    ... some code using variables ...
    test2

test2.m (matlab)

... some more code using same variables ...

Calling test runs the code in test as well as the code in test2.

Is there a similar way for python, to put ... some more code ..., into an external file, that will simply be read as if it is in the file that it is called from?

Answer 1

Sure!

#file  -- test.py --
myvar = 42
def test_func():
    print("Hello!")

Now, this file ("test.py") is in python terminology a "module". We can import it (as long as it can be found in our PYTHONPATH) Note that the current directory is always in PYTHONPATH, so if use_test is being run from the same directory where test.py lives, you're all set:

#file -- use_test.py --
import test
test.test_func()  #prints "Hello!"
print (test.myvar)  #prints 42

from test import test_func #Only import the function directly into current namespace
test_func() #prints "Hello"
print (myvar)     #Exception (NameError)

from test import *
test_func() #prints "Hello"
print(myvar)      #prints 42

There's a lot more you can do than just that through the use of special __init__.py files which allow you to treat multiple files as a single module), but this answers your question and I suppose we'll leave the rest for another time.