[C++] 模板类的多个可变参数包解决方案 | Multiple Variadic Parameter Pack for Template Class

[yangruihan]

模板类的多个可变参数包解决方案

参考：

• https://stackoverflow.com/questions/37200391/multiple-variadic-parameter-pack-for-template-class
• https://stackoverflow.com/questions/34940875/parameter-pack-must-be-at-the-end-of-the-parameter-list-when-and-why

解决方案

可以使用std::tuple来进行包装

如下：

template <typename attribute_tuple, APITypes APIType,
          typename policy_tuple> class IShader;

template <AttributeType... Attributes, APITypes APIType,
          class... Policies>
class IShader<std::tuple<Attributes...>, APIType,
              std::tuple<Policies...>> : public Policies... {

// ...

};

可以按照下面的方式来使用模板类：

IShared<std::tuple<Attribute1, Attribute2>, APITypeFoo,
        std::tuple<Policy1, Policy2>> ishared_instance;