Use Protected Constructors to Block Undesirable Object Instantiation

iteye_15479

于 2009-09-20 21:35:30 发布

阅读量100

点赞数

CC 4.0 BY-SA版权

分类专栏： c++ 文章标签： Access

本文链接：https://blog.youkuaiyun.com/iteye_15479/article/details/81766095

c++ 专栏收录该内容

38 篇文章

订阅专栏

本文介绍如何通过将构造器声明为受保护来阻止类实例化的方法。此外，还探讨了使用纯虚函数达到相同目的的可能性及其运行时开销。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

Use Protected Constructors to Block Undesirable Object Instantiation

In order to block creation of class instances, you can declare its constructor as protected.

 
class CommonRoot {
	protected: CommonRoot(){}//no objects of this class can be instantiated
};

class Derived: public CommonRoot {
public: Derived() {}
};

Derived d; // OK, constructor of d has access to any protected member in its base class
CommonRoot cr; //compilation error: attempt to access a protected member of CommonRoot

The same effect of blocking instantiation of a class can be achieved with pure virtual functions. However, these add runtime and space overhead. When pure virtual functions aren't needed, you can use a protected constructor instead.

Danny Kalev