具有常规STL接口的最大大小的数组，类似于boost :: array [英] Max-sized array with normal STL interface, similar to boost::array

问题描述

boost中是否有一个类似于array的类，它是一个类似于POD的类型，带有一个数组，但在容器中提供了可变数量的项目.也就是说，我想说的是数组最多包含10个项目，但在任何给定时刻可能包含0到10个项目.

Is there a class in boost similar to array which is a POD-like type with an array but provides for a variable number of items in the container. That is, I want to say the array has at most 10 items, but may contain from 0 to 10 items at any given moment.

boost::array将size()固定为常数N，因此它不能作为向量替代品的替代品.特别是，我希望结构的读者不知道它是静态数组，他们可以像使用其他容器一样使用begin()和end().

boost::array unfortunately fixes size() to the constant N, so it can't work as a drop in replacement for a vector. In particular I'd like the readers of the structure not to know it is a static array, they can use begin() and end() like any other container.

很明显，如果push_back()增长超出容量，则必须通过例外处理.

Obviously push_back() would have to through an exception if it would grow beyond the capacity.

首选在boost中已经存在的东西.

Something already in boost would be preferred.

注意:必须是类似于 POD的数据类型.为了清楚起见，包括内容(它们本身将采用POD类类型)在内的整个数组类对象必须类似于POD.这是出于序列化/复制的原因(以及与该序列化/复制相关的性能).

NOTE: it must be a POD-like data type. For clarity, the entire array-like object, included the contents (which will themselves by POD-like types) must be POD-like. This is for serialization/copying reasons (and for performance related to that serialization/copying).

像POD一样，我的意思是:

By POD-like I mean:

• 具有编译时常量大小
• 可以放心地

对于那些说无效或不可能的人.对此没有什么独到之处. boost::array是类似POD的类型.所要做的就是为当前大小添加一个额外的字段，以使其成为我想要的.我正在寻找已经存在的实现(因此已经过正确测试/维护).

For those who say it can't work or isn't possible. There is nothing ingenious about this. The boost::array is a POD-like type. All it would take is adding one extra field, for the current size, to make that into what I want. I'm looking for an implementation that already exists (and is thus properly tested/maintained).

推荐答案

问题是(可能是)初始化.你如何初始化 大小(如果是POD)?您如何执行不变式 size()< = max_size?

The problem is (probably) initialization. How do you initialize the size, if it is a POD? How do you enforce the invariant size() <= max_size?

从技术上讲，定义一些东西很容易，但是是否 这是有用还是安全的是另一个问题.你为什么不 只需使用boost :: array，并保持当前大小为 一个单独的变量?

Technically, it would be easy to define something, but whether it would be useful or safe is another question. Why don't you just use boost::array, and maintain your current size as a separate variable?

- 詹姆斯·坎泽(James Kanze)

-- James Kanze

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