Principles, anti-patterns and practical tips to design simpler, more maintainable systems.
Introduction
KISS stands for "Keep It Simple, Stupid" — a blunt but effective reminder: prefer simple solutions over complex ones. Simplicity reduces mental overhead and makes code easier to understand, modify, and debug.
What is KISS?
The KISS principle emphasizes minimalism in design: do not add features, abstractions, or indirections unless they solve a real problem. Simple systems often outperform complex ones in terms of reliability and speed of change.
Why simplicity matters
- Faster onboarding: new developers understand simple code faster.
- Fewer bugs: less code and fewer interactions mean fewer places for things to go wrong.
- Lower cost of change: simpler code is easier to modify and test.
- Better performance: simpler algorithms often have fewer layers and overhead.
Common complexity smells
- Deeply nested conditionals and loops.
- Excessive abstraction or indirection (many layers of interfaces for simple logic).
- Overuse of design patterns in places where a simple function would suffice.
- Large methods doing many things.
- Configuration scattered across many files for a single, small behavior.
Techniques to keep it simple
- YAGNI (You Aren't Gonna Need It): don’t implement features or abstractions for hypothetical future needs.
- Small functions: prefer short, focused functions with meaningful names.
- Clear naming: good names reduce the need for comments and explanations.
- Prefer composition over inheritance: composition often leads to clearer, simpler designs.
- Limit abstractions: introduce interfaces only when multiple implementations are expected.
- Refactor often: keep the codebase tidy; regular refactoring prevents complexity accumulation.
- Documentation where needed: document the "why" for non-obvious decisions rather than the "what".
Examples: complex vs simple
Complex example
// A complex approach with many layers and indirections
interface DataFetcher { Data fetch(Query q); }
class CachingFetcher implements DataFetcher { /* caching layer */ }
class RemoteFetcher implements DataFetcher { /* remote call */ }
class FetchFacade {
private final Pipeline pipeline;
Data getData(Query q) { return pipeline.execute(q); }
}
// A lot of wiring and layers for a simple GET operation
Simple alternative
// Start with a direct implementation and extract layers only when needed
class SimpleFetcher {
Data getData(Query q) {
// direct remote call
}
}
// Add caching or interface later if you actually need different implementations
The simple solution works until there's a demonstrated need for extension. Premature layering increases cognitive load.
When to accept complexity
Sometimes complexity is unavoidable. Accept it when:
- Requirements genuinely require it (e.g., distributed consensus, complex domain logic).
- There is measurable benefit (performance, reliability, extensibility) that justifies the cost.
- You have adequate tests and documentation to manage the complexity safely.
Conclusion & further reading
KISS is a practical compass: prefer the simplest design that satisfies the requirements. Combine KISS with DRY and SOLID to balance simplicity with good engineering practices. Always evaluate trade-offs and refactor bravely when complexity grows.
Further reading: articles on YAGNI, The Pragmatic Programmer, and clean code resources by Robert C. Martin.
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