Python’s Per-Module State

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Alright, one of my favorite topics Python’s per-module state! This is a concept that can be confusing for some newbies out there, but don’t worry bro!, because I’m here to break it down in the most casual way possible.

First things first, let’s define what we mean by “per-module state”.In Python, modules are essentially just files that contain code. When you import a module into your program, all of its variables, functions, and classes become available to use in your own code. But here’s the kicker these imported variables don’t necessarily have their own values! Instead, they share the same value as the variable with the same name in the original module file.

This might sound a bit weird at first, but it actually makes sense when you think about it. Let me give you an example to illustrate what I mean:

# my_module.py
# This is a module file that contains a list and a function to add elements to the list.

my_list = [1, 2, 3] # This is a list with three elements.

def add_to_list(x): # This is a function that takes in a parameter x.
    my_list.append(x) # This line appends the parameter x to the list my_list.

# main.py
import my_module # This line imports the module my_module.

print("Original list:", my_module.my_list) # This line prints the original list from the module.

my_module.add_to_list(4) # This line calls the function add_to_list from the module and adds the number 4 to the list.

print("List after adding 4:", my_module.my_list) # This line prints the updated list from the module.

In this example, we have a module called `my_module` that defines a variable `my_list` and a function `add_to_list`. When we import the `my_module` into our main program (`main.py`) using the `import` statement, all of its variables become available to us in `main.py`, including `my_list`.

Now, when we call the `add_to_list` function from within `main.py`, it modifies the original list that was defined in `my_module.py`. This is because both `main.py` and `my_module.py` are sharing the same variable (`my_list`)!

This might seem a bit confusing at first, but trust me once you get used to it, Python’s per-module state can be incredibly powerful for organizing your code into reusable modules that share data and functionality. Plus, it makes debugging easier because all of the variables are in one place!

I hope this helps clarify any confusion you might have had about this concept.

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