std::enable_shared_from_this<T>::operator=

 

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std::enable_shared_from_this

受保护成员函数

enable_shared_from_this::enable_shared_from_this

enable_shared_from_this::~enable_shared_from_this

enable_shared_from_this::operator=

公开成员函数

enable_shared_from_this::shared_from_this

enable_shared_from_this::weak_from_this (C++17)

 

enable_shared_from_this<T>& operator=( const enable_shared_from_this<T> &obj ) noexcept;		(C++11 起)

不做任何事；返回 *this 。

参数

obj

-

赋值给 *this 的 enable_shared_from_this

返回值

*this

注意

私有的 std::weak_ptr<T> 成员不受此赋值运算符影响。

示例

注意：定义 enable_shared_from_this::operator= 为受保护以避免意外切片，但允许导出类拥有默认的赋值运算符。

运行此代码

#include <memory>
#include <iostream>
 
class SharedInt : public std::enable_shared_from_this<SharedInt>
{
public:
    explicit SharedInt(int n) : mNumber(n) {}
    SharedInt(const SharedInt&) = default;
    SharedInt(SharedInt&&) = default;
    ~SharedInt() = default;
 
    // 两个赋值运算符都使用 enable_shared_from_this::operator=
    SharedInt& operator=(const SharedInt&) = default;
    SharedInt& operator=(SharedInt&&) = default;
 
    int number() const { return mNumber; }
 
private:
    int mNumber;
};
 
int main() {
    std::shared_ptr<SharedInt> a = std::make_shared<SharedInt>(2);
    std::shared_ptr<SharedInt> b = std::make_shared<SharedInt>(4);
    *a = *b;
 
    std::cout << a->number() << std::endl;
}

输出：

4

参阅

shared_ptr (C++11)

拥有共享对象所有权语义的智能指针 (类模板)