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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