How to import other Python files

Question

How do I import other files in Python?

1. How exactly can I import a specific python file like import file.py?
2. How can I import a folder instead of a specific file?
3. I want to load a Python file dynamically at runtime, based on user input.
4. I want to know how to load just one specific part from the file.

For example, in main.py I have:

from extra import * 

Although this gives me all the definitions in extra.py, when maybe all I want is a single definition:

def gap():
    print
    print

What do I add to the import statement to just get gap from extra.py?

Answer 1

1. Just import file without the '.py' extension.

2. You can mark a folder as a package, by adding an empty file named __init__.py.

3. You can use the __import__ function. It takes the module name as a string. (Again: module name without the '.py' extension.)

   pmName = input('Enter module name:')
   pm = __import__(pmName)
   print(dir(pm))
   

   Type help(__import__) for more details.