有没有理由在标准库中没有std :: identity？ [英] Is there a reason why there is not std::identity in the standard library?

问题描述

在用C ++处理通用代码时，我会找到一个 std :: identity 函子（例如 std :: negate ）非常有用。

When dealing with generic code in C++, I would find a std::identity functor (like std::negate) very useful. Is there a particular reason why this is not present in the standard library?

推荐答案

在引入std :: identity之后不久，出现问题了吗？开始出现，与与cdp98之前的std :: identity的定义冲突以扩展名出现： https://groups.google.com/a/isocpp.org/forum/#!topic/std-proposals/vrrtKvA7cqo
该网站可能会更多历史记录。

Soon after std::identity was introduced, issues began to appear, starting with conflicts to pre-cpp98 definitions of std::identity appearing as extensions: https://groups.google.com/a/isocpp.org/forum/#!topic/std-proposals/vrrtKvA7cqo This site might give a little more history for it.

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