嵌套数据成员指针 - 不可能？ [英] Nested data member pointer - not possible?

问题描述

下面的缩减代码示例不会做任何有用的，但是两个后续的分配到数据成员指针。第一个assignement工作，第二个赋予编译器错误。大概是因为它是一个嵌套的成员。

The foolowing reduced code sample does not do anything usefull but two subsequent assignments to a data member pointer. The first assignement works, the second one gives a compiler error. Presumably because its to a nested member.

问题是：真的只是不可能让一个成员指针指向嵌套的成员，或者我缺少任何奇特的语法

Question would be: Is it really just not possible to let a member pointer point to a nested member or am I missing any fancy syntax there?

struct Color {
    float Red;
    float Green;
    float Blue; };


struct Material {
    float Brightness;
    Color DiffuseColor; };


int main() {
    float Material::* ParamToAnimate;
    ParamToAnimate = &Material::Brightness;       // Ok
    ParamToAnimate = &Material::DiffuseColor.Red; // Error! *whimper*
    return 0; }

ATM我正在使用字节偏移和大量的转换。但是这是丑陋的，我更喜欢使用那些成员指针。

ATM I am working around by using byte offsets and a lot of casts. But that is ugly, I would better like to use those member pointers.

是的，我知道这个问题肯定会发生（像几乎任何问题）。是的，我事先搜索过，但没有找到满意的答案。

Yes, I know that question surely arised before (like nearly any question). Yes, I searched beforehand but found no satisfying answer.

感谢您的时间。

推荐答案

AFAIK，这是不可能的。指向成员的指针只能由类型& qualified_id 的表达式形成，这不是您的情况。

AFAIK, this is not possible. A pointer-to-member can only be formed by an expression of type &qualified_id, which is not your case.

Vite Falcon的解决方案可能是最合适的解决方案。

Vite Falcon's solution is probably the most appropriate.

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