a_SRP

Single Responsibility Principle (SRP)

📖 What is SRP?

The Single Responsibility Principle (SRP) states:

A class should have only one responsibility (one job) and only one reason to change.

Instead of creating one large class that performs multiple tasks, split the responsibilities into separate classes.

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❌ Before (SRP Violation)

The OrderService class performs multiple responsibilities:

• Place Order
• Save Order
• Send Email
• Generate Invoice
• Print Receipt

If any one of these features changes, the OrderService class must also change.

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✅ After (SRP Followed)

Each responsibility is moved into its own class.

• OrderService → Coordinates the order process
• BookingService → Places the order
• DatabaseService → Saves the order
• EmailService → Sends confirmation email
• InvoiceService → Generates and prints invoices

Now every class has only one responsibility.

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📂 Project Structure

01-Single-Responsibility-Principle
│
├── before/
│   └── SRP Violation
│
├── after/
│   └── SRP Implementation
│
└── README.md

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🎯 Benefits of SRP

• Cleaner code
• Easier to understand
• Easier to maintain
• Easier to test
• Easier to extend

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💡 Real-World Example

Think of an online shopping application.

Different people have different responsibilities:

• 📦 Order Team → Places orders
• 💾 Database Team → Stores data
• 📧 Email Team → Sends emails
• 🧾 Billing Team → Generates invoices

Instead of one person doing everything, each person handles one specific task.

Similarly, in software, each class should focus on one responsibility.

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🚀 Key Takeaway

One Class = One Responsibility = One Reason to Change