How Can Refactoring Eliminate Friend Dependencies in Shared Resource Management?

Friend Dependency Removal and Refactoring in a Shared Resource Management Design

In object-oriented design, the "friend" dependency introduces a tight coupling between classes and raises maintenance concerns. To remove such dependencies while maintaining the functionality of a shared resource management design, a multi-step refactoring process is recommended.

Step 1: Introduce an Abstract Interface

The initial step involves replacing the "friend" dependency with an abstract interface, InternalInterface, which defines the operations previously accessible only to the friendly class.

Step 2: Move Operations to the Interface

The operations that constituted the "call" dependency are shifted from the ClassA implementation to the InternalInterface definition.

Step 3: Connect Interface and Implementation

To provide access to the InternalInterface, introduce a protected constructor and protected generalization relationship between ClassA and InternalInterface.

Step 4: Glue the Components

In the ClassAAccessor constructor, introduce a setInternalInterfaceRef() method that allows ClassAAccessor to obtain a reference to InternalInterface from ClassA.

Step 5: Use Internal Interface for Access

Implement the attachAccessor() method in ClassA to pass the internal interface reference to ClassAAccessor.

Step 6: Optimize Coupling (Optional)

For further decoupling, introduce a second interface, InternalClientInterface, to mediate between ClassAAccessor and InternalInterface.

Advantages:

• Eliminates the "friend" dependency according to UML 2.2 standards.
• Complies with coding guidelines that discourage "friend" usage.
• Provides a more explicit and maintainable design.

Disadvantages:

• May increase code complexity.
• Requires abstract interfaces that potentially affect the footprint of the design.
• Protected generalization relationships have limited UML representation support.

The above is the detailed content of How Can Refactoring Eliminate Friend Dependencies in Shared Resource Management?. For more information, please follow other related articles on the PHP Chinese website!