How can I execute a Python function directly from the command line?

Executing Python Functions from the Command Line

Question:

If I have the following Python code:

def hello():
    return 'Hi :)'

How can I execute this function directly from the command line?

Understanding the Issue:

Python scripts typically have a main() function that contains the code to be executed when the script is run. However, if this function is not present or the function you want to run is not the main function, it can be tricky to execute it directly from the command line.

Solution:

There are several methods to run a specific Python function from the command line using the -c (command) argument:

1. Importing the Module and Namespace Pollution:

$ python -c 'import foo; print foo.hello()'

This approach imports the foo module and directly calls the hello() function from it. However, it exposes the foo module's entire namespace to the interpreter.

2. Selective Import and No Namespace Pollution:

$ python -c 'from foo import hello; print hello()'

This method imports only the hello() function without polluting the interpreter's namespace. It's a cleaner and preferred approach if you want to minimize name conflicts.

3. Intermediate Import for Namespace Control:

$ python -c 'from foo import *; print hello()'

This option imports the entire foo module into the interpreter's namespace. While it eliminates the need to prefix function calls with the module name, it can lead to namespace pollution if the module contains many functions.

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