矢量的通用矢量在C + + [英] Generic vector of vectors in C++

问题描述

在C ++中有一个好的方法来实现（或伪造）一个向量的通用向量的类型？

Is there a good way in C++ to implement (or fake) a type for a generic vector of vectors?

忽略一个向量的向量一个好主意（除非有一些等价的东西总是更好）。假设它确实对问题建模，并且矩阵没有准确地建模问题。假设模板函数把这些东西作为参数确实需要操作结构（例如调用push_back），所以他们不能只是一个支持 [] [] 。

Ignore the issue of when a vector of vectors is a good idea (unless there's something equivalent which is always better). Assume that it does accurately model the problem, and that a matrix does not accurately model the problem. Assume also that templated functions taking these things as parameters do need to manipulate the structure (e.g. calling push_back), so they can't just take a generic type supporting [][].

我想要做的是：

template<typename T>
typedef vector< vector<T> > vecvec;

vecvec<int> intSequences;
vecvec<string> stringSequences;

但是这是不可能的，因为typedef不能模板。

but of course that's not possible, since typedef can't be templated.

#define vecvec(T) vector< vector<T> >

是关闭的，并且会保存在vecvec上操作的每个模板函数上重复的类型，

is close, and would save duplicating the type across every templated function which operates on vecvecs, but would not be popular with most C++ programmers.

推荐答案

您希望拥有template-typedefs。这是不是但目前的C ++支持。一种解决方法是执行

You want to have template-typedefs. That is not yet supported in the current C++. A workaround is to do

template<typename T>
struct vecvec {
     typedef std::vector< std::vector<T> > type;
};

int main() {
    vecvec<int>::type intSequences;
    vecvec<std::string>::type stringSequences;
}

在下一个C ++（称为c ++ 0x，c ++ 1x due到2010），这将是可能的：

In the next C++ (called c++0x, c++1x due to 2010), this would be possible:

template<typename T>
using vecvec = std::vector< std::vector<T> >;

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