


What are some best practices for writing maintainable and scalable Python code?
Jun 13, 2025 am 12:16 AMTo make Python code easy to maintain and adapt to future changes, the key is to have clear structure, simple logic and follow common specifications. First, we must clarify our responsibilities, modularly design, split different functions into independent functions or classes, each function only does one thing, and each class is only responsible for one type of behavior; second, we must control the length of the function to be within 20 lines, avoid excessive nesting, reduce coupling between classes, and give priority to combination rather than inheritance; third, we must have clear names, variable names are used with nouns (such as user_list), function names are started with verbs (such as save_user_to_db()), and class names are used as big camels (such as DataProcessor), avoid abbreviations to improve readability; fourth, we must use type prompts and document strings reasonably, add detailed docstrings to each function to explain input and output and exceptions; fifth, we must unify the code style, and use tools such as flake8, mypy, black and other tools for static checks and automatic formatting, and perform checks before submission and in the CI process to ensure that the code style is consistent and reduce low-level errors. Although persisting in these practices seems simple, it can significantly improve code quality and development efficiency.
When writing Python code, the key to making the code easy to maintain and adapt to future changes is to have clear structure, simple logic and follow common specifications. This is not only a question of writing the right syntax, but also accumulating details such as how to organize code, naming variables, and split functions.
Clarify responsibilities and modular design
Splitting different functions into independent functions or classes is the first step to maintaining code maintainability. A function only does one thing, and a class only takes care of one type of behavior, which will be much easier when subsequent modification or reuse.
- The function should not be too long, it is better to control it within 20 lines.
- Avoid having too many if/else or loops nested in a function
- Minimize coupling between classes, using combinations is better than inheritance
For example, if you have a piece of code that processes data and mixes the parts saved to the database, it is best to separate the two pieces into two functions. In this way, you only need to move one of the requirements.
You must "understand" the naming, don't save that little time
Variable names, function names, and class names must be known at a glance what they do. Don't write names like a, b, and func1 quickly. When maintaining, you will thank yourself for typing a few more letters at that time.
- Use nouns to represent variables (such as
user_list
) - Denote a function with a verb (such as
save_user_to_db()
) - Use a big camel (such as
DataProcessor
)
Some developers are used to abbreviation, such as calc_usr_cnt()
, but it is actually more intuitive to write it directly into calculate_user_count()
, especially when teamwork.
Use type prompts and document strings reasonably
Python is a dynamic language, but that doesn't mean you're giving up on type information. Adding type annotations reasonably not only allows the IDE to better help you check errors, but also allows other code-reading people to understand your intentions faster.
def get_user_info(user_id: int) -> dict: ...
At the same time, it is recommended to add docstring for each function to explain input and output, exception conditions, etc. It’s not just to just write a sentence, but to really explain the behavioral boundaries of this function.
Unified style, automatic inspection tools must not be missing
When writing code, you must have a unified style, such as indentation, spaces, quotes, etc. You can choose PEP8 or use Black to automatically format. The key is to keep the whole project consistent.
- Use flake8, mypy, black and other tools to do static checking
- Automatic formatting before submission to avoid human negligence
- Add lint checks to the CI process to prevent bad code from being merged into
These tools are almost ignored after configuration once, but they can help you avoid many low-level mistakes and style controversies.
Basically that's it. It doesn't seem complicated, but it's easy to be overlooked in daily development. As long as you insist on writing it more clearly and standardizedly, it will save a lot of time in debugging and reconstruction in the long run.
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