异常重复的模板模式非法调用非静态成员函数 [英] Curiously Recurring Template Pattern Illegal call of non-static member funciton

问题描述

最近，我一直在尝试大量模板元编程，尤其是使用CRTP时，遇到了标题错误.特别是错误C2352'MeshComponent :: InternalSetEntity':非法调用了非静态成员函数.

I've been attempting a lot of template meta programming lately, particularly using CRTP, and have come across the titular error. Specifically error C2352 'MeshComponent::InternalSetEntity': illegal call of non-static member function.

我的代码的一个最小，完整和可验证的摘要如下:

A Minimal, Complete, and Verifiable snippit of my code is as such:

Component.h

Component.h

class Entity //Forward declaration

template<class T, EventType... events>
class Component {
private:
    short entityID;
public:
    void SetEntity(Entity& _entity) { entityID = _entity.GetId(); T::InternalSetEntity(_entity); }
protected:  
    void InternalSetEntity(Entity& _entity) {}
};

MeshComponent.h

MeshComponent.h

#include "Component.h"
class MeshComponent : public Component<MeshComponent> {
    friend class Component<MeshComponent>;
protected:
    void InternalSetEntity(Entity& _entity);
};

MeshComponent.cpp

MeshComponent.cpp

#include "MeshComponent.h"
void MeshComponent::InternalSetEntity(Entity& _entity) {
    //Nothing yet
}

Entity.h

class Entity {
private:
    short id;
public:
    short GetId() {return id;}
};

我没有声明任何静态函数，也不想声明.实际上，我要求它们成为成员函数，因为它们将对实例特定的数据进行操作.

I am not declaring any static functions, nor do I want to. In fact I require these to be member functions as they will operate on instance specific data.

如果有人知道为什么会发生此错误，以及可能的解决方案，我将不胜感激.预先感谢.

If someone knows why this error is occurring and a possible solution to the problem I would greatly appreciate it. Thanks in advance.

推荐答案

您知道并确保 MeshComponent 继承自 Component< MeshComponent> ，但编译器不会知道:就 Component 的定义而言， Component< T> 和 T 是不相关的.您需要明确执行向下转换:

You know and ensure that MeshComponent inherits from Component<MeshComponent>, but the compiler doesn't know that: as far as it knows in the definition of Component, Component<T> and T are unrelated. You need to perform the downcast explicitly:

static_cast<T*>(this)->InternalSetEntity(_entity);

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