类本身不能具有静态constexpr成员实例吗? [英] Can't a class have static constexpr member instances of itself?
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问题描述
此代码给我类型不完整错误. 问题是什么?不允许类具有自身的静态成员实例吗? 有没有办法达到相同的结果?
This code is giving me incomplete type error. What is the problem? Isn't allowed for a class to have static member instances of itself? Is there a way to achieve the same result?
struct Size
{
const unsigned int width;
const unsigned int height;
static constexpr Size big = { 480, 240 };
static constexpr Size small = { 210, 170 };
private:
Size( ) = default;
};
推荐答案
有没有办法达到相同的结果?
Is there a way to achieve the same result?
通过相同结果",您是否特别打算将
Size::big
和Size::small
?在那种情况下,这可能足够接近了:
By "the same result", do you specifically intend the constexpr
-ness of
Size::big
and Size::small
? In that case maybe this would be close enough:
struct Size
{
const unsigned int width = 0;
const unsigned int height = 0;
static constexpr Size big() {
return Size { 480, 240 };
}
static constexpr Size small() {
return Size { 210, 170 };
}
private:
constexpr Size() = default;
constexpr Size(int w, int h )
: width(w),height(h){}
};
static_assert(Size::big().width == 480,"");
static_assert(Size::small().height == 170,"");
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