Encapsulation and abstract classes in Python: an in-depth guide

• Definition: Encapsulation is to hide data and methods in a class and expose only the necessary interfaces to control access to data.
• benefit:
  • ImproveSecurity: Data can only be accessed through class methods, and external code cannot modify it directly.
  • Improve maintainability: When modifying data inside the class, there is no need to worry about external code calls.
  • Improved flexibility: Internal storage can be changed as needed without affecting external code.

Achieve encapsulation:

• Use access modifiers (public, protected, private) to control access permissions.
• Use the self variable inside the class to reference the instance.
• Avoid direct access to instance properties outside the class.

Abstract class

• Definition: An abstract class is a special class that limits class behavior. It contains abstract methods that cannot be instantiated.
• Purpose:
  • Define an interface to force subclasses to implement these methods.
  • Prevent the creation of instances that do not implement all abstract methods.

Implement abstract class:

• Use @abstractmethod decorator to mark abstract methods.
• Implement all abstract methods in subclasses.
• Abstract classes cannot be instantiated directly, only subclass instances can be created.

The difference between abstract methods and ordinary methods:

• Abstract methods are not implemented and must be implemented in subclasses.
• Common methods have been implemented in the parent class and can be inherited and overridden by subclasses.

Advantages of abstract classes:

• Ensure that all subclasses implement the required behavior.
• Improve code maintainability: avoid incomplete or inconsistent implementations by enforcing abstract methods.
• Promote interface consistency: Using the same abstract class in multiple modules can ensure interface consistency.

Disadvantages of abstract classes:

• Increased implementation complexity: all abstract methods must be implemented in subclasses.
• Possible lack of flexibility: subclasses cannot freely modify abstract methods.

The difference between encapsulation and abstract class

feature	Encapsulation	Abstract class
Purpose	Control data access	Restrict class behavior
Scope	Internal class	Parent class and subclass
Mandatory	Optional	Mandatory
Implementation	Access modifier	Abstract method
Subclass	Inheritable parent class methods	All abstract methods must be implemented
Instantiation	Instanceable	Not instantiable

Application scenarios

Package:

• Sensitive data protection.
• Management of complex data.
• Improve code maintainability.

Abstract class:

• Define common interface.
• Ensure consistent behavior for inherited classes.
• Achieve polymorphism.

Best Practices

• Use encapsulation moderately and hide only necessary data.
• When using abstract classes, consider the implementation complexity and flexibility of subclasses.
• Use the abstractmethod suffix in abstract method names to improve code readability.
• When implementing an abstract method in a subclass, use super() to call the parent class implementation to take advantage of reuse.

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