Context Managers in Python

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Context Managers in Python

Ever encountered the with statement? I've seen them around lots of times, but once, when asked about Context Managers during an interview, I didn't know what they were! Here's what to know about them, so you won't repeat my mistake.

You might've used it without realizing it, especially while working with files. For instance:

with open('test.txt', 'w') as f:
   f.write('Test')

Why do we need a Context Manager in Python anyway?

Managing resources like files, databases, or network connections is very common in programming. Ensuring these resources are appropriately released/closed after usage is vital to prevent issues like hanging connections or file access problems.

Context Managers help by:
1️⃣ Managing resources, ensuring safe usage and disposal.
2️⃣ Executing clean-up operations, like closing files or connections, even when errors pop up.
3️⃣ Enhancing code readability and ease of refactoring.

For Data Engineers, why should this matter?

While constructing a data pipeline that involves acquiring and releasing resources (like files or database connections), a context manager ensures proper closure, even after errors.

Wondering how to define a Context Manager?

A class just needs to implement two magical dunder methods: __enter__() (which produces the resource) and __exit__() (which handles cleanup). See below a simple example illustrating how context managers work behind the scenes.