Refactoring in C++¶

Definition¶

Refactoring is the process of improving the internal structure of existing code without changing its external behavior. The goal is to make C++ programs easier to read, maintain, and extend over time.

Why Refactor?¶

Improve code readability
Reduce technical debt
Make future changes easier
Eliminate duplicated logic
Simplify complex functions or classes
Improve testability
Increase overall maintainability

Key Principles¶

Behavior must not change.
Small, incremental steps
Continuous testing
Understand why a refactor is needed before doing it
Prefer clarity over cleverness

Common C++ Refactoring Techniques¶

Rename Variables and Functions¶

Use clear, descriptive names:

// Before
int x;

// After
int maxConnectionCount;

Extract Functions¶

Break large functions into smaller, reusable ones:

void processUser() {
    validateUser();
    saveUser();
    sendNotification();
}

Eliminate Duplicate Code¶

Move repeated logic into shared functions or utility classes.

Replace Magic Numbers with Constants¶

const int MAX_RETRIES = 3;

Prefer RAII and Smart Pointers¶

Use std::unique_ptr and std::shared_ptr instead of manual new/delete.

Simplify Conditionals¶

// Before
if (status == 1 || status == 2 || status == 3)

// After
bool isActive = (status >= 1 && status <= 3);

Encapsulate Data¶

Replace raw public fields with getters/setters or class methods to enforce invariants.

Break Up Large Classes (Class Decomposition)¶

Split classes that have too many responsibilities (related to the Single Responsibility Principle).

Use Standard Library Algorithms¶

Replace manual loops with STL algorithms:

std::sort(vec.begin(), vec.end());

When to Refactor?¶

Before adding new features
When fixing bugs
When code becomes hard to understand
During regular cleanup cycles
When reviewing code (PR feedback)

When Not to Refactor¶

When you do not understand the existing code behavior
When tests are missing (add tests first)
When deadlines require new features immediately
When refactoring would introduce unnecessary churn

Refactoring Tools for C++¶

clang-tidy
cppcheck
IDE support: CLion, Visual Studio, VSCode extensions
Automatic formatting: clang-format

Refactoring Checklist¶

[ ] Code still compiles
[ ] All tests pass
[ ] Behavior unchanged
[ ] Names are clear and expressive
[ ] No duplicate logic
[ ] Functions/classes have a single responsibility
[ ] Code is easier to read than before
[ ] Document any structural changes