Module Creation

To define a module, simply use your text editor to type some Python code into a text file, and save it with a “.py” extension; any such file is automatically considered a Python module. All the names assigned at the top level of the module become its attributes (names associated with the module object) and are exported for clients to use.

For instance, if you type the following def into a file called module1.py and import it, you create a module object with one attribute—the name printer, which happens to be a reference to a function object:

def printer(x):                   # Module attribute
    print(x)

Before we go on, I should say a few more words about module filenames. You can call modules just about anything you like, but module filenames should end in a .py suffix if you plan to import them. The .py is technically optional for top-level files that will be run but not imported, but adding it in all cases makes your files’ types more obvious and allows you to import any of your files in the future.