没有虚拟构造函数，但有虚拟析构函数 [英] No Virtual constructors but virtual destructor

问题描述

如果我们没有虚拟构造函数，那为什么还要有虚拟析构函数呢?构造函数也可以是虚拟的吗?

If we dont have virtual constructors then why we have virtual destructors? Can constructors also be virtual?

推荐答案

• 虚拟构造函数没有意义-您确切声明了什么 类型已创建，并且在编译时众所周知.编译器 不需要[实际上不需要，因为动态分配是基于 关于仅在创建对象之后才创建的信息]. 因此，没有虚拟构造函数.
• 虚拟析构函数对于防止内存泄漏很重要，并且 监视系统.假设您有A* a = new B; [B继承 从A]开始，之后又是delete a;-编译器无法 知道a是B(在一般情况下)，并将调用A的 析构函数-如果它不是虚拟的，则可能会发生内存泄漏， 或其他故障.
• 使用虚拟析构函数-您确保B的析构函数为 调用，因为B对象被破坏.
• There is no point in virtual constructor - you declare exactly what type is created, and it is well known in compile time. The compiler do not need [and actually cannot, since the dynamic dispatch is based on information which is created only after the object was created]. So there are no virtual constructors.
• Virtual destructors are important to prevent memory leaks, and monitor the system. Assume you have A* a = new B; [B inherits from A], and you later delete a; - the compiler has no way of knowing a is a B [in the general case], and will invoke A's destructor - if it wasn't virtual, and you might get a memory leak, or other faults.
• Using virtual destructor - you ensure that B's destructor is invoked, since a B object is being destroyed.

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