Fundamental Coding Principles

Apply this skill to keep code changes focused, testable, and maintainable.

Quick Checklist

• Confirm each edit has a single purpose before coding.
• Ruthlessly remove duplication or dead paths you touch.
• Only add behavior backed by an explicit requirement.
• Prefer simple, composable solutions over clever ones.
• Keep truthy data and decisions in one authoritative place.

Principle Guardrails

SOLID

• S: Validate the change impacts one reason to vary; split helpers if mixed concerns appear.
• O: Extend behavior through new types or functions rather than rewriting stable code paths.
• L: Ensure new subtype logic preserves caller expectations (inputs, return contracts, exceptions).
• I: Create targeted interfaces; avoid forcing consumers to implement unused members.
• D: Depend on abstractions or injected collaborators; eliminate hardwired globals where possible.

DRY

• Scan for repeated logic, constants, or schemas; consolidate into shared utilities before finishing.
• Prefer extracting reusable modules over copy-pasting even inside the same file.

KISS

• Trim optional branches, flags, and polymorphism unless they solve today’s requirement.
• Keep functions short and state minimal; decompose complex flows into readable steps.

YAGNI

• Challenge every new feature, parameter, or hook: is there a verified need right now?
• Defer premature abstractions until duplication or clear requirements emerge.

SSOT

• Update or create the canonical definition (config, schema, doc) when data models change.
• Remove divergent caches or mirrors unless you enforce sync in the same change.

Reference Playbooks

• Splunk: "SOLID Design Principles – Hands-On Examples" – success/failure code walkthroughs for each letter.
• PullRequest.com: "7 Clean Coding Principles" – DRY-focused review prompts.
• MIT 6.031: Code Review Guide – DRY and simplification questions to ask.
• Baeldung: KISS Software Design Principle – tactics for keeping solutions lightweight.
• TechTarget: YAGNI Explainer – decision tests and risk scenarios.
• Atlassian Workstream: Building an SSOT – practices for maintaining canonical sources.