Effective Refactoring: Balancing Principles and Practicality

how principles can sometimes lead to unnecessary complexity in your code. Discover when it's better to prioritize simplicity and clarity.

The reality of a developer’s day-to-day work doesn’t leave room for perfectionism. Refactoring is essential for maintaining healthy codebases as It ensures that software remains maintainable, scalable, and resilient to future changes. But in the real world, developers often deal with tight deadlines, business goals, and legacy systems.

Martin Fowler defines refactoring as :

The process of changing a software system in such a way that it does not alter the external behavior of the code yet improves its internal structure.

When done correctly, refactoring:

• Improves readability: Makes the code easier to understand.

• Enhances maintainability: Simplifies future changes and debugging.

• Reduces technical debt: Prevents long-term costs by addressing issues early.

In this article we will explore how to approach refactoring effectively and realistically, balancing principles like DRY (Don’t Repeat Yourself) and SOLID with the realities of our day to day, but let’s first explore how to identify the code that needs us to invest time in.

How to Identify Code That Needs Refactoring

I once inherited an e-commerce system from an outsourcing company that was terminated due to system quality issues. The main issues were that items frequently went vanished from the inventory, quantities were updating randomly and whenever a patch was made, some thing else broke.

I have dealt with a lot of similar cases to learn that this is a sign to refactor. The signals that I use to determine that are:

1. Frequent Bugs in same module: If the same module repeatedly causes issues, it’s a candidate for refactoring.

2. Hard-to-Read Code: If understanding a function feels like deciphering a riddle, it needs simplification.

3. Slow Development: Fixing bugs took forever due to high coupling.

4. Duplication: Functions were cloned everywhere.

5. Code Rot: Functions or modules with too many responsibilities.

It doesn’t make sense to strictly follow principles on a huge codebase when things are this bad. We need a balance that will maintaining a rational timeline while following best practices like avoiding duplication.

Balancing DRY and Simplicity

The DRY principle advocates eliminating duplicate code, but it can lead to over-abstraction. For example, pulling out shared logic into a single function can inadvertently couple unrelated modules. While DRY promotes efficiency, sometimes copy-paste is the better choice if it preserves clarity and independence.

For example imagine you have methods to send notifications The first example is focused a lot on the DRY principle, that it breaks single-responsibility.

function sendNotification(recipient, message, type) {
  const formattedMessage = formatMessage(type, message);
  const validatedRecipient = validateRecipient(type, recipient);
  send(type, validatedRecipient, formattedMessage);
}

function formatMessage(type, message) {
  if (type === 'email') return formatEmailMessage(message);
  if (type === 'sms') return formatSMSMessage(message);
  // other types...
}

function validateRecipient(type, recipient) {
  if (type === 'email' && !isValidEmail(recipient)) {
    throw new Error('Invalid email');
  }
  if (type === 'sms' && !isValidPhoneNumber(recipient)) {
    throw new Error('Invalid phone number');
  }
  // other types...
}

The second example strikes the balance between both only if you have to send two or more types of notifications. And we can argue that it would have broke the You Aint Gonna Need It (YAGNI) principle if done when having one type of notification to send.

class Notification {
  constructor(recipient, message) {
    this.recipient = recipient;
    this.message = message;
  }

  validate() {
    throw new Error('Validate method must be implemented.');
  }

  format() {
    throw new Error('Format method must be implemented.');
  }

  send() {
    throw new Error('Send method must be implemented.');
  }

  process() {
    this.validate();
    const formattedMessage = this.format();
    this.send(formattedMessage);
  }
}

class EmailNotification extends Notification {
  validate() {
    if (!isValidEmail(this.recipient)) {
      throw new Error('Invalid email address');
    }
  }

  format() {
    return formatEmailMessage(this.message);
  }

  send(formattedMessage) {
    sendEmail(this.recipient, formattedMessage);
  }
}

class SMSNotification extends Notification {
  validate() {
    if (!isValidPhoneNumber(this.recipient)) {
      throw new Error('Invalid phone number');
    }
  }

  format() {
    return formatSMSMessage(this.message);
  }

  send(formattedMessage) {
    sendSMS(this.recipient, formattedMessage);
  }
}

This brings us to the other challenge we need to stay aware of, over engineering.

The Cost of Over engineering

SOLID principles aim to make software more robust and flexible, but rigid adoption can result in needless complexity. In the example above, implementing an elaborate inheritance hierarchy for a single-use case might violate YAGNI (You Aren’t Gonna Need It).

Creating a balance between extensibility and simplicity is crucial, especially when refactoring. The focus should alway be on what we have now, as it is what will resolve business impacting side effects. Immediate business impact should be prioritized, and the technical goals should be aligned with adding business value. This will make it easier to get a buy in from stakeholders with all the competing priorites.

Competing Priorities

Deadlines often trump code cleanliness. Developers must weigh the costs of refactoring against delivering features on time. In some cases, the immediate business impact of shipping outweighs the long-term benefits of a cleaner codebase.

Strategies for Real-World Refactoring

1. Focus on Business-Critical Code Prioritize refactoring areas that directly impact business outcomes. For example, improving the performance of a payment processing module is more valuable than cleaning up an infrequently used admin tool.

2. Refactor Incrementally Big-bang refactors are risky and time- consuming. Instead, adopt the Boy Scout Rule: leave the code cleaner than you found it. Small, incremental changes accumulate over time, making the codebase more maintainable without disrupting ongoing development.

3. When to break DRY: If two pieces of code are similar but exist in different contexts, duplicating them might be better than introducing a shared dependency.

4. When to break SOLID: Violating the Single Responsibility Principle (SRP) might be acceptable in a stable, low-risk module where the cost of abstraction outweighs the benefits.

5. Test-Driven Refactoring: Before refactoring, write tests to capture the current behavior of the code. These tests act as a safety net, ensuring that changes don’t introduce new bugs. Refactoring is much safer when you can verify functionality at every step.

Practical Examples of Real-World Refactoring

1. Simplifying a Monolithic Function

Before:

function calculateOrder(customer, items) {
  let discount = 0;
  if (customer.type === 'premium') {
    discount = items.length > 5 ? 0.2 : 0.1;
  }
  let total = items.reduce((sum, item) => sum + item.price, 0);
  total -= total * discount;
  if (customer.hasLoyaltyCard) {
    total *= 0.95;
  }
  return total;
}

After:

function calculateOrder(customer, items) {
  const discount = getDiscount(customer, items);
  let total = calculateTotal(items, discount);
  return applyLoyaltyDiscount(customer, total);
}

function getDiscount(customer, items) {
  if (customer.type !== 'premium') return 0;
  return items.length > 5 ? 0.2 : 0.1;
}

function calculateTotal(items, discount) {
  return items.reduce((sum, item) => sum + item.price, 0) * (1 - discount);
}

function applyLoyaltyDiscount(customer, total) {
  return customer.hasLoyaltyCard ? total * 0.95 : total;
}

Breaking the function into smaller methods makes it easier to understand and test.

2. Avoiding Over-Abstraction

Suppose you have two similar but not identical processes:

function renderPDF(document) {
  // Render PDF logic
}

function renderImage(document) {
  // Render Image logic
}

Abstracting this might create unnecessary complexity if their shared logic is minimal. Instead, leaving them separate maintains clarity and independence.

When Not to Refactor

Refactoring isn’t always the right choice. Avoid it when:

1. Deadlines are tight: Focus on delivering functionality unless refactoring is necessary for the feature.

2. The code is stable: Refactoring low-risk, rarely updated code offers little value.

3. It adds complexity: Don’t refactor for refactoring’s sake; changes should simplify the code.

Balancing Effectiveness and Principles

Software engineering is as much about making trade-offs as it is about following principles. DRY and SOLID are excellent guidelines but shouldn’t be dogmatically applied. Effective refactoring is about balancing perfection with the real world challenges of time, resources, and business priorities. Remember, Better is better than perfect.

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