Law of Demeter (LoD) Explained in Seconds

The Law of Demeter (LoD): Keep Your Code Loosely Coupled

The Law of Demeter (LoD) is a design guideline aimed at reducing coupling in your code. Its core principle is simple: "Only talk to your immediate friends, not to strangers."

In essence, a class or module should only interact directly with objects it depends on, avoiding interactions with objects those objects depend on. This promotes simpler, more testable, and less interconnected code.

Anti-Pattern (Avoid):

<code>// Tight coupling through nested calls
customerCity := order.GetCustomer().GetAddress().GetCity()
fmt.Printf("Customer lives in: %s\n", customerCity)</code>

This example demonstrates tight coupling. Changes to the Order, Customer, or Address classes could break this code.

Improved Approach:

<code>// Decoupled using a single method call
customerCity := order.GetCustomerCity()
fmt.Printf("Customer lives in: %s\n", customerCity)</code>

The GetCustomerCity() method encapsulates the complexity, hiding the internal structure and reducing dependencies.

Benefits of LoD:

• Reduced Coupling: Easier to maintain and modify code with fewer interdependencies.
• Improved Readability: Code becomes more straightforward and easier to understand.
• Information Hiding: Internal implementation details are shielded from external components.
• Easier Testing: Simplifies testing by reducing the need for complex mocks.

Applying LoD in Practice:

• Employ Data Transfer Objects (DTOs) to manage data flow.
• Utilize Facade patterns to simplify interactions with complex subsystems.
• Refactor chained method calls into single, higher-level methods.

Further Exploration:

Interested in learning more about software design principles? Explore these related concepts:

• Dependency Inversion Principle (DIP)
• Golang Dependency Injection
• Interface Segregation Principle (ISP)
• You Aren't Gonna Need It (YAGNI) Principle
• Liskov Substitution Principle (LSP)
• Keep It Simple, Stupid (KISS) Principle
• Don't Repeat Yourself (DRY) Principle
• Tell, Don't Ask Principle

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