stl容器与std :: unique_ptr的对boost :: ptr_container [英] stl container with std::unique_ptr's vs boost::ptr_container

问题描述

有了c ++ 11，我问自己，如果有一个替换boost :: ptr_containers在c ++ 11。我知道我可以使用a std :: vector< std :: unique_ptr< T> > ，但我不知道这是否是一个完全替代。

解决方案

它们真正解决了两个相似但不同的问题。

指针容器是一种在容器中存储对象的方法，这种方法恰恰是指向分配的内存而不是值的指针。他们会尽其所能隐藏它们是指针容器的事实。这意味着：

• 容器中的条目不能为空。


• 您从迭代器和


• 使用许多标准算法可能会很麻烦。而棘手，我的意思是破碎。指针容器有自己内置的算法。

但是，指针容器知道它们可以提供一些新的功能：

• A clone


• 容器释放其对象的所有权的能力（在一个对象的所有者之后）

他们真的是完全不同的概念。有很多的东西，你必须手动做的指针容器可以自动用专门的函数。

如果你真的需要一个容器的指针，那么您可以使用 unique_ptr 的容器。但是如果你需要存储一堆你分配的对象，并且你想玩涉及所有权等的特殊游戏，那么指针容器不是一个坏主意。

With c++11 out there, I was asking myself if there is a replacement of the boost::ptr_containers in c++11. I know I can use e.g. a std::vector<std::unique_ptr<T> >, but I'm not sure if this is a complete replacement. What is the recommended way of handling these cases?

解决方案

They really solve two similar but different problems.

A pointer container is a way to store objects in a container that just so happen to be pointers to allocated memory rather than values. They do everything in their power to hide the fact that they are a container of pointers. This means:

• Entries in the container cannot be NULL.
• Values you get from iterators and functions are references to the type, not pointers to the type.
• Working with many standard algorithms can be... tricky. And by "tricky", I mean broken. Pointer containers have their own built-in algorithms.

However, the fact that pointer containers know that they're containers of pointers, they can offer some new functionality:

• A clone member function that performs a deep copy, via the use of a certain "Cloneable" concept on the type of the object.
• The ability of a container to release ownership of its objects (after a shallow copy, for example).
• Built-in functions to transfer ownership to other containers.

They really are quite different concepts. There is a lot of stuff you would have to do manually that pointer containers can do automatically with specialized functions.

If you really need a container of pointers, then you can use containers of unique_ptr. But if you need to store a bunch of objects that you happen to heap allocate, and you want to play special games with them involving ownership and such, then the pointer containers are not a bad idea.

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