5.1 Coding Standards And Maintainable Code

Maintainable code is code that future people can safely understand and change. Those future people include your teammates, your replacement, and you after three months of other work.

Coding standards are not about making everyone identical. They reduce unnecessary decision cost so the team can spend attention on design and behavior.

What standards should cover

Useful standards are concrete:

• Naming conventions for domain concepts.
• File and module organization.
• Error handling and logging expectations.
• Validation boundaries.
• Testing expectations.
• Documentation rules for public APIs and surprising decisions.
• Formatting and linting automated by tools.

Avoid standards that require endless subjective debate. If a tool can enforce it, let the tool do the boring work.

Maintainability signals

Look for:

• Functions with one clear purpose.
• Names that reveal domain meaning.
• Small public interfaces.
• Local reasoning: you can understand a change without loading the whole system into your head.
• Tests near the behavior they protect.
• Comments that explain why, not what the code already says.

Documentation in code

Good documentation is not a wall of comments. It answers questions a maintainer would naturally ask:

• Why is this rule here?
• What external constraint forced this shape?
• What should not be changed casually?
• What incident or decision led to this behavior?

Write comments where future confusion would be expensive.