默认的模板类型可以是通用引用吗？ [英] Can a defaulted template type be universal reference?

问题描述

以下是&&& 是否为通用参考？

  template< class Function = std :: greater< int> > void f（Function&& f = Function（））; 
     <$ class $>  / code>是Scott Meyers编写的用于区分正则右值引用（即 int&& 和模板代码中的右值引用）的术语， code> T&&& 。这是很重要的，因为参考折叠规则与模板代码发挥作用，所以这个术语用于辅助教学。它被称为反转引用的原因是它可以绑定到任何东西。
 
 
 
请记住，在C ++语言中不是通用引用这样的东西， Function&& 是 。但是，在Scott Meyer的术语中， Function&& 是一个通用引用 / p> 
In the following, is && a universal reference ?
template <class Function = std::greater<int> > void f(Function&& f = Function());

解决方案
The term universal reference is a made up term by Scott Meyers to make a distinction between normal rvalue references, i.e. int&& and rvalue references in template code, i.e. T&&. This is important because of the reference collapsing rules that come into play with template code, so this term is used to aid in teaching. The reason it is called a unversal reference is because it can bind to anything.

Just keep in mind that there is no such thing as a universal reference in the C++ language, Function&& is a rvalue reference as far as the language is concerned. However, yes, in Scott Meyer's made up terminology, Function&& is a universal reference in your example.

                        
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