使课程不可复制*并且*不可移动 [英] Make a class non-copyable *and* non-movable

问题描述

在C ++ 11之前，我可以使用它来使类不可复制:

Before C++11, I could use this to make a class non-copyable:

private:
MyClass(const MyClass&);
MyClass& operator=(const MyClass&);

使用C ++ 11，我可以改为:

With C++11, I can do it like this instead:

MyClass(const MyClass&) = delete;
MyClass& operator=(const MyClass&) = delete;

在将类与已删除的副本和分配一起使用时，是否有可能生成默认的move运算符?并且该类不是被完全复制，而是毕竟被移动了(有点相似)?

When using the class with the deleted copy and assignment, is there a chance that a default move operator is generated? And the class is not exactly copied, but moved (which is sort of similar) after all?

因此，我是否必须这样做以防止默认移动构造和分配:

So, do I have to do this to prevent default move construction and assignmnent:

MyClass(MyClass&&) = delete;
MyClass& operator=(MyClass&&) = delete;

...?

推荐答案

正如注释中已经提到的其他内容一样，C ++ 11中引入了删除的构造函数.要回答您的问题，通常遵循以下规则:

As others already mentioned in the comments, deleted constructors was introduced in C++11. To answer your question, the following rules hold in general:

1. 这两个复制操作是独立的.声明副本构造函数不会阻止编译器生成副本分配，反之亦然. (与C ++ 98中的相同)
2. 移动操作不是独立的.声明其中一个会阻止编译器生成另一个. (不同于复制操作.)
3. 如果声明了任何复制操作，则不会生成任何移动操作. (根据您的情况)
4. 如果声明了任何移动操作，则不会生成任何复制操作.这与以前的规则相反.
5. 如果声明了析构函数，则不会生成任何移动操作.仍会生成复制操作，以实现与C ++ 98的反向兼容性.
6. 仅当未声明构造函数时才生成默认构造函数. (与C ++ 98中的相同)

1. The two copy operations are independent. Declaring copy constructor does not prevent compiler to generate copy assignment and vice versa. (Same as in C++98)
2. Move operations are not independent. Declaring either one of them prevents the compiler to generate the other. (Different from copy operations.)
3. If any of the copy operations is declared, then none of the move operation will be generated. (Your case.)
4. If any of the move operation is declared, then none of the copy operation will be generated. This is the opposite rule of the previous.
5. If a destructor is declared, then none of the move operation will be generated. Copy operations are still generated for reverse compatibility with C++98.
6. Default constructor generated only when no constructor is declared. (Same as in C++98)

根据评论的要求，以下是一些资料来源(C ++ 11是

As requested in the comments, here are some sources (C++11 is draft N3242):

• 复制操作:§12.8.8，§12.8.19
• 移动操作:第12.8.10节，第12.8.21节
• 默认构造函数:第12.1.5节

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