请帮助我理解这种语法(在C ++中实现静态断言) [英] Please help me understand this syntax (implementing static assert in C++)
问题描述
此语法用作此问题答案的一部分:
This syntax was used as a part of an answer to this question:
template <bool>
struct static_assert;
template <>
struct static_assert<true> {}; // only true is defined
#define STATIC_ASSERT(x) static_assert<(x)>()
我不明白这个语法。它是如何工作的?
假设我做
STATIC_ASSERT(true);
它会转换为
static_assert<true>();
现在是什么?
推荐答案
STATIC_ASSERT(true);
确实意味着
static_assert<true>();
static_assert< true>
只是一个没有任何成员的空结构。 static_assert< true>()
创建该结构的对象,不会将其存储在任何位置。
which evaluates to nothing. static_assert<true>
is just an empty structure without any members. static_assert<true>()
creates an object of that structure and does not store it anywhere.
另一方面
STATIC_ASSERT(false);
表示
static_assert<false>();
这会导致编译错误。 static_assert
没有专门为 false
。所以使用一般形式。但是一般的形式如下:
which results in compilation error. static_assert
has no specialization for false
. So a general form is used. But the general form is given as follows:
template <bool>
struct static_assert;
这只是一个结构的声明,而不是它的定义。因此, static_assert< false>()
会导致编译错误,因为它试图创建未定义的结构的对象。
which is just a declaration of a structure and not its definition. So static_assert<false>()
causes compilation error as it tries to make an object of a structure which is not defined.
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