如何销毁对象，但不能释放内存? [英] How can I destroy an object, but not free the memory?

问题描述

大家好，

我正在编写一个内存池应用程序，但遇到以下问题:

当我开始时，应用程序正在分配(通过使用malloc)大量的内存.然后，一个char指针列表指向分配的内存的不同位置.当我调用分配时，将返回这些指针之一.

问题是，当我调用deallocate时，我只想显式地调用对象的析构函数，然后使内存块再次可用.换句话说，我不想释放内存.

所以我的解除分配看起来像这样:

Hello people,

I am writing a memory pool application and I have the below problem:

When I start, the application is allocating (by using malloc) a big amount of memory. Then, a list of char pointers point to different places of the allocated memory. When I call allocate, one of these pointers is returned.

The problem is, when I call deallocate, I only want to explicitly call the destructor of the object and then make the memory block available again. In other words, I do not want to free the memory.

So my deallocate looks like that:

void Pool:: Deallocate(void* pObj)
{
.. Call object destructor here ..

m_ListOfSlices.push_back((char*)pObj);
m_AllocLeft += 1;
}

如何调用pObj指向的对象的析构函数?

请记住，我真的不需要模板解决方案.

由于操作员删除，必须有一种方法实际上是在做同样的事情！我尝试调试运算符delete，但是我没有运气.

请帮忙！

修改后的:::
非常感谢您的回答，

要回答答案1，恐怕您实际上可以做到.您实际上可以执行pMem->~A();，然后调用delete pMem;

要回答问题2，我很早以前就读过parashift教程，问题是它们根本不适用于我的情况；).我正在尝试做另一件事.不过，非常感谢您的答复:)

How can I call the destructor of the object that pObj points to?

Keep in mind that I do not really want a template solution.

There must be a way, since operator delete, is actually doing the same thing! I tried to debug the operator delete, but I had no luck.

Please help!

Revised:::
Thanks very much for your answers,

To answer answer 1, I am afraid you can actually do that. You can actually do pMem->~A(); and then call delete pMem;

To question answer2, I have read the parashift tutorials long ago, the problem is that they do not apply to my situation at all ;) . I am trying to do a different thing. Thanks very much for the reply though :)

推荐答案

为什么您不简单地在对象中提供一个clear()方法来清理对象呢?

顺便说一句，对我来说，您的池设计看起来不是C ++:首先您要调用malloc(纯C语言)，然后要操作void指针并将其转换为char指针...这似乎真的一团糟.
通常，当您想要一个池时，它主要用于存储相同类型的对象.因此，在这种情况下，您不需要做所有这些丑陋的事情.

您实际上有什么要求?您正在尝试精确地做什么?

Why don''t you simply provide a clear() method in your object that takes care of cleaning your object ?

By the way, your design of the pool doesn''t look very C++ to me: first you are calling malloc (which is pure C) and then you are manipulating void pointers and casting them to char pointers... It really seems to be a mess.
In general, when you want to have a pool, it is mainly used to store objects of the same type. So in that case there''s no need for all these ugly stuff you are doing.

What are your requirements in fact ? What are you trying to do precisely ?

让我们开始一些步骤:

• 无需构造即可分配:仅使用malloc或强制转换new char数组的返回值.
  

Lets go for steps:

• Allocate without contruct: just use malloc, or cast the return of a new char array.
  

A* pA;
pA = (A*)new char[sizeof(A)];

构造原始分配的内容:使用new放置:

Construct what is rawly allocate: use placement new:

new(pA)A(...);

销毁而不取消分配:显式调用析构函数:

Destroy without deallocate: explicitly call the destructor:

pA->~A();

取消分配已被销毁的内容:在分配它时使用free或释放char数组

Deallocate what has already been destroyed: use free or free the char array as you allocated it

delete[] (char*)pA; pA = 0;

分配和构造:只需使用new

Allocate and construct: just use new

pA = new A(...);

销毁并取消分配:只需使用delete

Destroy and deallocate: just use delete

delete pA; pA = 0;

您可以调用它，但您不应该.在这里查看[^ ]有关详细信息.
:)

You may call it, but you shouldn''t. See here [^] for details.
:)

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