Lambda运算符重载表达式 [英] Lambda expression for operator overloading

问题描述

是否可以为重载运算符编写lambda表达式?

Is it possible to write lambda expression for overloading operators?

例如，我具有以下结构:

For example, I have the following structure:

struct X{
    int value;
    //(I can't modify this structure)
};

X需要==运算符

int main()
{
    X a = { 123 };
    X b = { 123 };
    //[define equality operator for X inside main function]
    //if(a == b) {}
    return 0;
}

可以将

==运算符定义为bool operator==(const X& lhs, const X& rhs){...}，但这需要添加一个单独的函数，而我的比较仅在特定函数内有效.

== operator can be defined as bool operator==(const X& lhs, const X& rhs){...}, but this requires adding a separate function, and my comparison is valid only within a specific function.

auto compare = [](const X& lhs, const X& rhs){...}将解决该问题.我想知道我是否可以将此lambda编写为运算符.

auto compare = [](const X& lhs, const X& rhs){...} will solve the problem. I was wondering if I can write this lambda as an operator.

推荐答案

是否可以为重载运算符编写lambda表达式?

Is it possible to write lambda expression for overloading operators?

否.

运算符重载函数必须是函数或函数模板.它们可以是成员函数，成员函数模板，非成员函数或非成员函数模板.但是，它们不能是lambda表达式.

Operator overload functions must be functions or function templates. They can be member functions, member function templates, non-member functions, or non-member function templates. However, they cannot be lambda expressions.

来自 C ++ 11 Standard/13.5重载的运算符，第6 :

运算符应为非静态成员函数或为非成员函数，并至少具有一个参数，其类型为类，对类的引用，枚举或对枚举的引用.

An operator function shall either be a non-static member function or be a non-member function and have at least one parameter whose type is a class, a reference to a class, an enumeration, or a reference to an enumeration.

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