如何初始化静态向量成员？

问题描述

例如

struct A
{
    static vector<int> s;
};

vector<int> A::s = {1, 2, 3};

但是，我的编译器不支持初始化列表。任何方式来实现它很容易？ lambda函数有帮助吗？

However, my compiler doesn't support initialization list. Any way to implement it easily? Does lambda function help here?

推荐答案

没有什么特别优雅的。您可以从静态数组复制数据，也可以使用函数调用的结果初始化它。前者可能会使用更多的内存，而后者需要一些稍微杂乱的代码。

There's nothing particularly elegant. You can either copy the data from a static array, or initialise it with the result of a function call. The former might use more memory than you'd like, and the latter needs some slightly messy code.

Boost有一个，使其略显丑陋：

Boost has a library to make that slightly less ugly:

#include <boost/assign/list_of.hpp>
vector<int> A::s = boost::assign::list_of(1)(2)(3);

是的，它可以让你不必为一个函数命名一个初始化向量：

Yes, it can save you from having to name a function just to initialise the vector:

vector<int> A::s = [] {
    vector<int> v;
    v.push_back(1);
    v.push_back(2);
    v.push_back(3);
    return v;
}();

（严格来说，这应该有一个明确的返回类型， [] ） - > vector< int> ，因为lambda主体不仅仅包含一个 return 语句，一些编译器将接受我的版本，相信它将在2014年成为标准。）

(Strictly speaking, this should have an explicit return type, []()->vector<int>, since the lambda body contains more than just a return statement. Some compilers will accept my version, and I believe it will become standard in 2014.)

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