当不支持可变参数模板参数时，如何为元组专门化一个类模板? [英] How to specialize a class template for a tuple when variadic template arguments are not supported?

问题描述

我有一个班级模板

template<class T>
class A
{...};

当 T 是一个元组时，我想专门化它.我想我可以做到这一点

and I want to specialize it when T is a tuple. I think I can do this

template<class Args...>
class A<std::tuple<Args...>>
{...};

但是，我的编译器不支持可变参数模板参数，怎么办?

However, my compiler doesn't support variadic template arguments, how to do it?

推荐答案

您可以将其专门用于各种不同数量的元组:

You can specialize it for tuples of every different arity:

// explicit specialization for 0-element tuples
template<>
class A<std::tuple<>>
{...};

// partial specialization for 1-element tuples
template<class Arg>
class A<std::tuple<Arg>>
{...};

// partial specialization for 2-element tuples
template<class Arg0, class Arg1>
class A<std::tuple<Arg0, Arg1>>
{...};

... 依此类推，直到您需要支持的元组元素的最大数量.

... and so on, up to whatever maximum number of tuple elements you need to support.

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