> For the complete documentation index, see [llms.txt](https://ga0-2.gitbook.io/seifxr10anz-content/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ga0-2.gitbook.io/seifxr10anz-content/python-cheatsheet/modules.md).

# Modules

A module is a file with a ".py" extension and contains Python code. They can define functions, variables, classes, and can also include runnable code.

You can use modules that are already included when you install Python, from files that you write yourself, or come from a 3rd-party source (usually PyPi). You just have to `import` it (and, if necessary, install it first).

#### `import`

Import a module

```python
import datetime

print(datetime.date.today())
```

Import a specific object from a module

```python
from datetime import date

print(date.today())
```

Import more than one specific object from a module

```python
from datetime import date, datetime

print(date.today())
print(datetime.now())
```

Give imported objects an alternative name

```python
from datetime import date as d, datetime as dt

print(d.today())
print(dt.now())
```

Import *all* objects from a module

```python
from datetime import *

print(date.today())
print(datetime.now())
```

#### Writing your own modules

Any Python file you write is already a module and any identifiers in your file (variables, functions, classes) are automatically "exported".

When your module gets imported by another file, all code in it will execute as if it were run as a standalone script (i.e. running a script in the command line `python3 my_script.py`). Most of the time, you don't want this so it's good practice to only run code when your file was explicitly executed as a standalone script and not imported. You do that by including this block of code at the bottom of your file:

```python
if __name__ == '__main__':
    print('Running as a stand-alone script, not a module')
    # Call your functions here
```