C++ 模板 typedef
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C++ template typedef
提问by Notinlist
I have a class
我有一堂课
template<size_t N, size_t M>
class Matrix {
// ....
};
I want to make a typedefwhich creates a Vector(column vector) which is equivalent to a Matrixwith sizes N and 1. Something like that:
我想typedef创建一个Vector（列向量），它相当于一个Matrix大小为 N 和 1 的a 。类似这样的东西：
typedef Matrix<N,1> Vector<N>;
Which produces compile error. The following creates something similar, but not exactly what I want:
这会产生编译错误。以下创建了类似的东西，但不完全是我想要的：
template <size_t N>
class Vector: public Matrix<N,1>
{ };
Is there a solution or a not too expensive workaround / best-practice for it?
是否有解决方案或不太昂贵的解决方法/最佳实践？
回答by GManNickG
C++11 added alias declarations, which are generalization of typedef, allowing templates:
C++11 添加了别名声明，它是 的泛化typedef，允许模板：
template <size_t N>
using Vector = Matrix<N, 1>;
The type Vector<3>is equivalent to Matrix<3, 1>.
该类型Vector<3>等效于Matrix<3, 1>.
In C++03, the closest approximation was:
在 C++03 中，最接近的近似值是：
template <size_t N>
struct Vector
{
typedef Matrix<N, 1> type;
};
Here, the type Vector<3>::typeis equivalent to Matrix<3, 1>.
在这里，类型Vector<3>::type等效于Matrix<3, 1>。
