How to avoid class inflation in C++ class design?

Tips to avoid class bloat in C++ include: using composition and aggregation instead of inheritance, and avoiding duplication and ambiguity. Avoid inheriting diamond structures. Use the Interface Separation Principle to decompose interfaces into smaller, specific-purpose interfaces.

Tips to avoid class bloat in C++ class design

In C++, class bloat refers to the unexpected increase in the size of a class and the properties and methods it contains. a massive increase. This can negatively impact performance and maintainability. Here are some tips to avoid class bloat:

1. Use composition and aggregation

Composition and aggregation are two techniques that replace inheritance. They allow the creation of relationships between classes without Causes expansion.

• Composition: Container classes have instances of other classes as member variables. Container classes do not inherit properties or methods from other classes, but delegate them to member objects.
• Aggregation: Container classes reference instances of other classes as member variables. The two classes are conceptually independent, but the container class is responsible for maintaining references.

2. Avoid inheriting the diamond structure

Inheriting the diamond structure means that a class inherits from two or more base classes, causing the properties and methods of these base classes to be in the derived class Repeatedly. This leads to class bloat and possibly ambiguity.

3. Use the Interface Separation Principle

The Interface Separation Principle stipulates that interfaces should be decomposed into smaller, purpose-specific interfaces. This helps avoid class bloat because a class only needs to implement the interfaces it really needs.

Practical case:

Consider a class used to manage student information:

class Student {
public:
  int id;
  std::string name;
  std::string address;
  std::string phone;
  std::string email;
  std::vector<Course> courses;
};

This class contains a large number of attributes and methods and is easy to bloat. It can be improved by using the principles of composition and interface separation:

class Person {
public:
  int id;
  std::string name;
  std::string address;
  std::string phone;
  std::string email;
};

class Student : public Person {
public:
  std::vector<Course> courses;
};

// 其他不需要课程信息的类
class Employee : public Person {
  // ...
};

// 接口或抽象基类
class ICourseManager {
public:
  virtual void enroll(Student* student, Course* course) = 0;
  virtual void unenroll(Student* student, Course* course) = 0;
};

By moving the personal information into the Person base class and abstracting the course management functionality using the ICourseManager interface , we avoid class bloat while maintaining class maintainability and extensibility.

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