更改对象的"this"指针以指向其他对象 [英] Change 'this' pointer of an object to point different object

问题描述

class C{
   //methods and properties
}

void C::some_method(C* b){
    delete this;
    this = b;     
}

这使我在编译时出现以下错误:

This gives me follwing error when compiling:

error: lvalue required as left operand of assignment

我的意图:假设存在类C的对象a和b.类C的内容可能非常庞大，并且逐字段复制可能会非常昂贵.我希望以一种经济的方式将" a "的所有内容替换为" b ".

My intention: Say there are objects a and b of class C. The contents of the class C can be very huge and field by field copying can be very costly. I want all the contents of 'a' to be replaced by 'b' in an economical way.

默认副本构造函数将执行预期的任务吗?

Will default copy constructor do the intended task?

我发现了一个叫做移动构造函数"的东西 http://akrzemi1.wordpress.com/2011/08/11/move-构造函数/

I found something called 'move constructor' http://akrzemi1.wordpress.com/2011/08/11/move-constructor/

也许，它可能会达到我想要的效果.

Perhaps, it might get the effect that I want.

推荐答案

this 指针是指向要在其上下文中工作的对象的隐式指针，您不能重新分配它.

The this-pointer is an implicit pointer to the object in whose context you are working, you cannot reassign it.

根据Stroustrup的圣经(我拥有的C ++编程语言，第三版)，此表示为

According to Stroustrup's bible (The C++ Programming Language, 3rd edition I have) this is expressed as

C * const this

表示您有一个指向类 C 的常量指针，因此，如果您尝试更改它，编译器将抱怨.

meaning you have a constant pointer to your class C, so the compiler will complain if you try to change it.

正如我所纠正的，上述表达式不能完全正确地描述 this ，因为 this 实际上是一个右值.

As I was corrected, the above mentioned expression does not describe this fully correctly, for this is actually an rvalue.

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