C ++在非成员函数中使用'this'无效[duplicate]

This question already has an answer here:

这个问题在这里已有答案:

Invalid use of 'this' in non-member function 1 answer

在非成员函数1答案中无效使用'this'

I have the error "invalid use of 'this' in non-member function"

我有错误“在非成员函数中无效使用'this'”

What is the correct way to write the code to avoid this error.

编写代码以避免此错误的正确方法是什么。

tree.h:

#ifndef TREE_H
#define TREE_H

template <typename T>
class Node;

class Tree
{
public:
    Tree();

    template <typename TNodeType>
    Node<TNodeType> elaborate(Node<TNodeType> &node);

    Tree* self();

    void doSomething();
};

template <typename TNodeType>
Node<TNodeType> createNew() {
    Node<TNodeType> model(this); //<-- ERROR HERE
    return model;
}

#endif // TREE_H

node.h:

#ifndef NODE_H
#define NODE_H

#include <tree.h>

template <typename TNodeType>
class Node
{
public:
    Node(Tree *tree);

    TNodeType current();

private:
    Tree *_tree;
};

template <typename TNodeType>
Node<TNodeType>::Node(Tree *tree):
    _tree(tree)
{
    _tree->doSomething();
}

template <typename TNodeType>
TNodeType Node<TNodeType>::current()
{
    //some code here
}

#endif // NODE_H

Solved.

In tree.h I skipped the declaration of:

在tree.h中,我跳过了以下声明:

template <typename TNodeType>
Node<TNodeType> createNew();

And I had forgotten in the definition "Tree::" before "createNew()"

我在“createNew()”之前忘记了“Tree ::”这个定义

I agree that this question could have been avoided ;-). Sorry

我同意这个问题可以避免;-)。抱歉

2 个解决方案

#1

createNew() is a free function (i.e. not a member of a class), and therefore has no notion of this.

createNew()是一个*函数(即不是类的成员),因此没有这个概念。

#2

template <typename TNodeType>
Node<TNodeType> createNew() {
    Node<TNodeType> model(this); //<-- ERROR HERE
    return model;
}

It's really no member function. this is keyword of C++ language, that can be used only in member functions.

它真的没有会员功能。这是C ++语言的关键字,只能在成员函数中使用。

#1