SOLID Principles in 2025: Evolution, Not Extinction

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Every few months, some conference speaker declares the death of SOLID principles with the confidence of someone who's just discovered a revolutionary truth. They're wrong.

After spending 12 years leading engineering teams across three tech stacks, I've watched SOLID principles morph—not die. Their core value remains intact, but their application has fundamentally shifted.

The 2025 SOLID Reality

👉 Single Responsibility Principle
No longer about class design alone. Today it's function purity, module boundaries, and service domains. A modern SRP violation isn't a bloated class—it's a microservice handling three distinct business concerns.

👉 Open/Closed Principle
Composition over inheritance won. Full stop. We extend behavior through configuration, middleware chains, and plugin systems—not class hierarchies. React's component model exemplifies this perfectly.

👉 Liskov Substitution
The DNA of proper typing systems. TypeScript's structural typing and Go's interfaces both implement Liskov's vision without requiring traditional inheritance.

👉 Interface Segregation
GraphQL's field-level resolution and the API Gateway pattern both embody this—clients request exactly the interface they need. No bloat.

👉 Dependency Inversion
Dependency injection containers, hooks patterns, and context providers all implement this in ways Uncle Bob never envisioned but would recognize instantly.

The Practical Value

When teams abandon these principles entirely, technical debt accumulates at frightening speed. The principles still solve real problems—just in modern clothing.

SOLID isn't gospel; it's a battle-tested heuristic that continues to evolve with our tools.

Takeaway: Don't throw away decades of engineering wisdom because patterns changed. Update your implementation, not your fundamentals.

DALLE prompt:
"A metaphorical image of classical architecture (columns labeled S-O-L-I-D) being remodeled into a sleek, modern building, warm color palette, digital art."