Why You Shouldn't Nest Your Code

Summary

In this video, the concept of 'never nesting' code is explored, advocating for keeping functions flat to improve readability and maintainability. The speaker introduces techniques like extraction and inversion to simplify complex, nested code. By extracting parts of functions into smaller, more focused functions and inverting conditions to reduce indentation, code becomes easier to follow. The philosophy is supported by Linus Torvalds’ guidelines, which emphasize that deep nesting leads to poor code structure. Ultimately, the video promotes writing clean, modular code by avoiding excessive nesting and focusing on simplicity.

Takeaways

• 😀 A 'never nester' is a programmer who avoids excessive nesting in their code to improve readability and maintainability.
• 😀 Nesting refers to adding inner blocks like loops or conditionals inside functions, increasing the complexity and cognitive load for programmers.
• 😀 The deeper the nesting, the harder it is to mentally process the code, especially when it exceeds three levels of indentation.
• 😀 Linus Torvalds is suspected of being a 'never nester' based on his coding style, where he limits nesting to three levels, in line with the Linux kernel’s guidelines.
• 😀 The maximum nesting depth a 'never nester' can handle is generally three levels, and going beyond this is considered a bad practice.
• 😀 Two main techniques to reduce nesting are 'extraction' and 'inversion'. Extraction involves moving inner logic to separate functions, while inversion flips conditions to reduce indentation.
• 😀 Extraction helps by breaking a large function into smaller, more focused functions, making the code more understandable and maintainable.
• 😀 Inversion involves changing the order of conditions and using early returns to flatten code, making the happy path clearer and reducing indentation.
• 😀 The speaker demonstrates refactoring a complex download manager function to flatten its structure, using both extraction and inversion techniques.
• 😀 The Linux kernel's style guide enforces limited indentation by setting the tab size to eight characters, preventing deep nesting and promoting cleaner, more efficient code.
• 😀 By limiting nesting and breaking down code into smaller functions with single responsibilities, developers can write cleaner, more readable, and easier-to-maintain code.

Q & A

What does 'never nester' mean in programming?

A 'never nester' is a programmer who avoids deeply nested code. They prefer to write functions that are shallow in structure, typically avoiding more than three levels of indentation to make the code easier to read and maintain.

Why do never nesters dislike deeply nested code?

Never nesters find deeply nested code difficult to follow mentally. As nesting increases, so does the complexity of the code, making it harder to hold multiple ideas in one's head at once. This increases the cognitive load for the developer.

How does nesting affect the readability of a function?

As nesting deepens, the readability of a function declines. More nested blocks require the reader to manage multiple conditions simultaneously, making it harder to understand the core logic of the function. This can slow down comprehension and debugging.

What are the two methods mentioned for reducing nesting in code?

The two methods for reducing nesting are extraction and inversion. Extraction involves pulling out nested code into separate functions, while inversion involves flipping conditions and using early returns to reduce nested blocks.

What is the purpose of extraction in refactoring code?

Extraction helps by moving deeply nested blocks of code into separate functions, thus reducing indentation and making the main function clearer. This helps the code be more readable and maintainable.

How does inversion help in reducing code nesting?

Inversion helps by flipping conditions so that the 'unhappy' path is handled first, allowing for an early return. This reduces the need for an 'else' block and minimizes nesting by flattening the control flow.

Can you explain the concept of 'early return' in inversion?

An early return is a technique where, instead of nesting code inside an 'else' block, you return from the function early if a certain condition is met. This helps avoid unnecessary indentation and keeps the code flow straightforward.

What example from the script demonstrates how extraction and inversion can be applied?

The example from the script involves refactoring a function responsible for downloading files. By extracting complex parts of the code, such as processing 'Pending' and 'InProgress' downloads into separate functions, and using inversion to simplify error handling, the code becomes more readable and manageable.

How does the Linux kernel enforce limitations on code nesting?

The Linux kernel style guidelines state that if code requires more than three levels of indentation, it should be refactored. They visually enforce this by setting the tab size to 8 characters wide, which makes deep nesting visually more apparent and discourages it.

What benefit does limiting nesting have on the overall quality of code?

Limiting nesting forces developers to write cleaner, more modular code with smaller functions that each have a single responsibility. This leads to better readability, easier debugging, and more maintainable code.