Python Modules and Namespaces, Managing Variables Across Files

In Python programming, understanding how variables are managed across different files or modules is critical to structuring your programs correctly. It’s a matter of scope and namespaces.

Namespaces and Scope

Firstly, we need to understand what a namespace is. In Python, a namespace is a mapping from names (variable names, function names, etc.) to objects. The important thing to note here is that there is no relation between names in different namespaces. Therefore, two different modules can both define a variable, my_var, without conflict, because each module has its own namespace.

For instance, consider two Python files:

In file1.py:

my_var = "Hello from file1"

In file2.py:

my_var = "Hello from file2"

The my_var in file1.py and file2.py are two distinct variables. They live in separate namespaces and do not interfere with each other.

Importing Variables Between Modules

While each module has its own namespace, Python allows you to access variables from one module in another using the import statement.

In file1.py:

my_var = "Hello from file1"

In file2.py:

from file1 import my_var
print(my_var)  # This will output: Hello from file1

Here, my_var in file2.py is the same as my_var in file1.py because it was imported. However, if my_var is subsequently redefined in file2.py, this change won’t affect the original my_var in file1.py.