How Do You Design Code That’s Built to Survive Change?
Object-oriented programming languages are designed to model reality both efficiently and effectively
When an object depends on another class, it creates a dependency.
To prevent the need for a complete rewrite in the future, inject dependencies and avoid tightly coupling objects.
Refactoring enables you to restructure existing code while maintaining its external behavior.
To improve design, must question each method and describe its responsibilities in one sentence. This approach lowers barriers to enhancing the design.
Even if the ultimate design is unclear, refactoring code can help clarify it.
Perform refactorings, even if the ultimate design is not yet determined.
Good practices help reveal design characteristics, especially when dealing with complex systems. When each method performs a single task, the class's purpose becomes more clear.
Professionals are defined by their work methods. Sound practices may serve well until better ones are discovered.
Experimenting becomes costly when software is not modular and easily testable.
A profession is an investment in our skills and long-term career fulfillment refactoring is the main skill to dominate where sound design doesn't exist in a legacy code base.
Most code issues come from two places: technical debt or a messy codebase.
Technical debt helps teams deliver quickly but must be paired with clean code.
Here’s how to tell the difference:
1. Check if the code is clean:
Look for clear structure and readability. Ensure there are no unnecessary complexities.
2. Confirm if the code is tested:
Verify that tests cover all important paths. Ensure tests run without errors.
3. Identify if there’s a learning objective:
Determine if the team learns from changes. Look for improvements in skills and practices.
4. Make sure there’s a payback plan:
Discuss how to address technical debt later. Set clear timelines for improvements.
5. Ensure the business is informed:
Keep stakeholders updated on code changes. Align technical decisions with business goals.
Understanding these points helps teams manage technical debt wisely.
Clean code leads to better results and fewer headaches.
Confidence in coding is a superpower. To tackle technical debt refactoring is the process to follow.
TDD builds your coding confidence by:
Catch Errors Early.
TDD helps find mistakes before they grow. When you test often, you spot issues fast. This keeps your code clean and strong.
Clear Understanding of Problems
TDD requires you to know what you are solving. You break down the problem into small parts. This clarity helps you write better code.
The TDD Mantra
The TDD Mantra guides your work. It tells you where to start and what to do next. This method creates a cycle of progress.
Evolving Features
TDD pushes your design to grow. Every new feature adds to your code’s strength. You learn to adapt and improve with each step.
Rapid Experimentation
TDD allows for quick tests and feedback. You can try new ideas without fear. This leads to better solutions and more confidence.
One final thought:
“Improvement is a continuous process.” —Unknown
How Do You Design Code That’s Built to Survive Change?
Object-Oriented Design (OOD) isn’t about writing perfect code. It’s about writing changeable code—systems that can evolve without collapsing under their own complexity.
The core goal? Organize dependencies in a way that makes future changes easier and safer.
Whether you're working on a greenfield project or updating a legacy system, keeping this one principle in mind can make or break long-term maintainability.
Design for Flexibility, Not for Fortune-Telling
You can’t predict future requirements. Most attempts to do so result in unnecessary code, wasted time, and increased complexity.
Here’s what to avoid:
Adding abstraction “just in case”
Writing code for imagined use cases
Building layers that don’t yet serve a purpose
When you code for potential scenarios instead of actual ones, you’re injecting friction into today’s workflow to prepare for a future that may never arrive.
Avoid speculative architecture. Design to solve today’s problems well.
Experimentation > Assumptions
One of the most overlooked practices in OOD is experimentation. Instead of baking in solutions based on assumptions, test your ideas:
Try simpler alternatives before introducing design patterns
Refactor incrementally as needs evolve
Use prototypes to validate design choices early
Don't let tools or frameworks dictate your architecture. The design should be driven by business needs, not by the features of your stack or the pressure to keep up with trends.
Only Add Structure When There’s a Need
Object-Oriented Design shines when it solves real-world problems:
Are parts of the system changing at different rates?
Is coupling between modules making updates risky or expensive?
Are responsibilities tangled between unrelated components?
If the answer is yes, applying OOD principles can help decouple responsibilities, isolate areas of change, and improve testability.
But if there’s no pressure, don’t overdesign. OOD isn’t about maximalism—it’s about making the design match the problem.
Characteristics of Well-Designed OOD Code
Good OOD doesn’t announce itself with complex hierarchies or pattern-heavy structures. Instead, it quietly supports your ability to evolve and reason about the system.
Here’s what to look for in quality OOD code:
1. Transparency
The impact of any change should be easy to spot. When a bug arises or a feature changes, you should know:
Where the logic lives
What modules are affected
What needs to be tested
Opaque code with tangled dependencies breaks this model. In contrast, transparent designs **reduce debugging time and testing overhead**.
2. Proportionality
Not every problem requires a framework or abstract class. Your code should only become more complex when **the value of doing so outweighs the cost**.
Examples:
A single interface to decouple two systems? Reasonable.
A deep inheritance tree with vague benefits? Probably overkill.
OOD is not about applying design patterns everywhere. It’s about applying the _right_ amount of structure at the _right_ time.
3. Reusability Without Fragility
Reusing code is a plus—but only if the code is safe to reuse.
Good OOD encourages:
Loose coupling (so reused code doesn’t pull in unrelated dependencies)
Clear contracts (so changes to reused components don’t cause breakage)
High cohesion (so units of code do one thing well)
Reusability should be a side effect of clear design, not a primary goal that compromises maintainability.
4. Context Independence
Code should work in multiple contexts without modification. This is one of the long-term payoffs of following OOD principles. When code can be plugged into new use cases or reused in different environments without rework, your overall system becomes far more agile.
Questions to ask yourself:
Can this class/module be used outside of its current use case?
Are dependencies clearly defined and minimal?
Does this object expose a clear and minimal interface?
If the answer to these is yes, your design is heading in the right direction.
When to Use OOD Principles
You don’t need OOD in every situation. But when the system has:
A growing codebase
Multiple collaborators
Shifting requirements
High maintenance cost
A need for long-term adaptability
Then applying OOD can pay off exponentially over time.
Use it to:
Reduce side effects
Isolate complexity
Improve testing and extensibility
Communicate intent more clearly through code structure
Don’t fall for overengineering.
Real-world Object-Oriented Design isn’t about cramming in SOLID principles or creating rigid class hierarchies. It’s about understanding the pressure points in your code and organizing responsibilities to reduce future cost.
Every line should earn its place.
When in doubt, default to the simplest thing that works. Then refactor when there’s a real, pressing need.
That’s how maintainable software gets built.