否定std :: integral_constant< bool> [英] negation of std::integral_constant<bool>

问题描述

对于这么简单的问题，很抱歉，但我找不到答案很容易。 Google对于C ++ negation integral_constant和类似的查询没有什么有趣的。

Sorry for asking so simple question, but I cannot find the answer easily. Google says nothing interesting about "C++ negation integral_constant" and similar queries.

在C ++ 11中有任何特性使 std :: true_type 从 std :: false_type ，反之亦然？换句话说，我想要更多的readeble版本

Is there in C++11 any trait that make std::true_type from std::false_type and vice versa? In other words, I'd like some more readeble version of

std::is_same<my_static_bool, std::false_type>

我知道当然可以自己写，但是我想使用现有的if有这样的。

I know of course I can write it myself, but I'd like to use the existing one if there is such.

推荐答案

没有，因为它本质上是一行和 type_traits> 应尽可能小。

There is not, because it's essentially a one-liner and the <type_traits> should be as small as possible.

template <typename T> using static_not = std::integral_constant<bool, !T::value>;

用法：

static_not<my_static_bool>

这是正确的方法，因为标准总是说 false_type 或派生自这样的，所以你不能依赖于等于 std :: false_type 。我通常放松到有一个constexpr布尔 :: value 属性，因为我不使用标签调度。

This is the correct way because the standard always says "false_type or derived from such", so you can't depend on being equal to std::false_type. I usually relax that to "having a constexpr boolean ::value property" because I don't use tag dispatching.

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