Introduction to DSA

🔹 Aspect-Oriented Programming (AOP)

**Aspect-Oriented Programming (AOP)** is a **programming paradigm** that helps in separating **cross-cutting concerns** (such as logging, security, and transaction management) from the main business logic of an application.

📌 Why Use AOP?

AOP is useful when you need to apply the **same functionality (like logging or security) across multiple parts** of an application without duplicating code.

✅ **Separation of Concerns** – Keeps business logic separate from secondary concerns.
✅ **Code Reusability** – No need to repeat code for logging, security, or transactions.
✅ **Improves Maintainability** – Changes to logging or security can be done in one place.
✅ **Enhances Readability** – Core business logic remains clean and understandable.

💡 Real-Life Example

Consider a **banking system** where every method (deposit, withdraw, transfer) requires **logging and security checks**. Instead of adding the same logging/security code in each method, AOP allows you to define it **once** and apply it everywhere.

🖥️ AOP in Java (Spring Boot Example)

Using **Spring AOP**, we can apply logging before and after method execution.


            import org.aspectj.lang.annotation.Aspect;
            import org.aspectj.lang.annotation.Before;
            import org.aspectj.lang.annotation.After;
            import org.springframework.stereotype.Component;
            
            @Aspect
            @Component
            public class LoggingAspect {
            
                @Before("execution(* com.bank.service.*.*(..))")
                public void logBeforeMethod() {
                    System.out.println("Logging BEFORE method execution...");
                }
            
                @After("execution(* com.bank.service.*.*(..))")
                public void logAfterMethod() {
                    System.out.println("Logging AFTER method execution...");
                }
            }

🖥️ AOP in Python (Using Decorators)

In Python, AOP can be implemented using **decorators**.


            def log_decorator(func):
                def wrapper(*args, **kwargs):
                    print(f"Executing {func.__name__}...")
                    result = func(*args, **kwargs)
                    print(f"Finished {func.__name__}.")
                    return result
                return wrapper
            
            class BankService:
                @log_decorator
                def deposit(self, amount):
                    print(f"Depositing ${amount}...")
            
            bank = BankService()
            bank.deposit(100)

🎯 Summary