为什么std :: allocator在C ++ 17中丢失成员类型/函数？

本文介绍了为什么std :: allocator在C ++ 17中丢失成员类型/函数？的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述 在查看 std :: allocator 时，我看到了以下成员： value_type ， 指针， const_pointer ， 引用， const_reference ， size_type ， difference_type 和 rebind 已全部弃用。 While looking at std::allocator, I see that members:value_type,pointer,const_pointer,reference,const_reference,size_type,difference_type, andrebind have all been deprecated. 分配者也将不再具有成员： 地址， max_size ，构造或破坏。 Allocators will also no longer have the members: address, max_size, construct, or destroy. 为什么会这样？ 推荐答案如果您查看相关的isocpp论文，您会发现现在想到的是您提到的第一个论文集最好放在 std :: allocator_traits 。自从STL（甚至不是标准库）问世以来，使用特征的转移就更多了。If you look at the relevant isocpp paper you can see that the first set you mention is now thought to be better placed in std::allocator_traits. Since the STL (not even standard library) came out, there's been more of a shift to use traits. 重新绑定也是遗物。首次发布STL时，不支持别名和模板模板参数。有了这些语言功能， rebind 似乎相当复杂。例如，如您在中看到的那样，在《 The C ++ Programming Language》，第4版，第34.4.1节，p 998，注释默认分配程序类中的经典重新绑定成员：rebind is also a relic. When the STL first came out, aliases and template-template parameters were not supported. With these language features in existence, rebind seems fairly convoluted. E.g., as you can see in an answer to this question, in The C++ Programming Language, 4th edition, section 34.4.1, p. 998, commenting the 'classical' rebind member in default allocator class :template<typename U> struct rebind { using other = allocator<U>;}; Bjarne Stroustupr写道：好奇的重新绑定模板是一个古老的别名。应该是：Bjarne Stroustupr writes this : "The curious rebind template is an archaic alias. It should have been:template<typename U>using other = allocator<U>;但是，分配器是在C ++支持此类别名之前定义的。 However, allocator was defined before such aliases were supported by C++."总的来说，这是赶上语言和范式转变的标准库。So, altogether, it's the standard library catching up with the language and paradigm shifts. 这篇关于为什么std :: allocator在C ++ 17中丢失成员类型/函数？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！